Maximum pods in an EC2 instance in EKS is dependent on the ENIs the ec2 instance has and the number of secondary IP addresses each ENI can have.

You can find the details of maximum ENIs per instance and IP addresses per ENI at - https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/using-eni.html#AvailableIpPerENI

As for the details of max pods per ec2 instance, it can be found at: https://github.com/awslabs/amazon-eks-ami/blob/master/files/eni-max-pods.txt

a1.2xlarge 58
a1.4xlarge 234
a1.large 29
a1.medium 8
a1.metal 234
a1.xlarge 58
c1.medium 12
c1.xlarge 58
c3.2xlarge 58
c3.4xlarge 234
c3.8xlarge 234
c3.large 29
c3.xlarge 58
c4.2xlarge 58
c4.4xlarge 234
c4.8xlarge 234
c4.large 29
c4.xlarge 58
c5.12xlarge 234
c5.18xlarge 737
c5.24xlarge 737
c5.2xlarge 58
c5.4xlarge 234
c5.9xlarge 234
c5.large 29
c5.metal 737
c5.xlarge 58
c5a.12xlarge 234
c5a.16xlarge 737
c5a.24xlarge 737
c5a.2xlarge 58
c5a.4xlarge 234
c5a.8xlarge 234
c5a.large 29
c5a.metal 737
c5a.xlarge 58
c5ad.12xlarge 234
c5ad.16xlarge 737
c5ad.24xlarge 737
c5ad.2xlarge 58
c5ad.4xlarge 234
c5ad.8xlarge 234
c5ad.large 29
c5ad.metal 737
c5ad.xlarge 58
c5d.12xlarge 234
c5d.18xlarge 737
c5d.24xlarge 737
c5d.2xlarge 58
c5d.4xlarge 234
c5d.9xlarge 234
c5d.large 29
c5d.metal 737
c5d.xlarge 58
c5n.18xlarge 737
c5n.2xlarge 58
c5n.4xlarge 234
c5n.9xlarge 234
c5n.large 29
c5n.metal 737
c5n.xlarge 58
c6g.12xlarge 234
c6g.16xlarge 737
c6g.2xlarge 58
c6g.4xlarge 234
c6g.8xlarge 234
c6g.large 29
c6g.medium 8
c6g.metal 737
c6g.xlarge 58
c6gd.12xlarge 234
c6gd.16xlarge 737
c6gd.2xlarge 58
c6gd.4xlarge 234
c6gd.8xlarge 234
c6gd.large 29
c6gd.medium 8
c6gd.metal 737
c6gd.xlarge 58
cc2.8xlarge 234
cr1.8xlarge 234
d2.2xlarge 58
d2.4xlarge 234
d2.8xlarge 234
d2.xlarge 58
d3.2xlarge 18
d3.4xlarge 38
d3.8xlarge 59
d3.xlarge 10
d3en.12xlarge 89
d3en.2xlarge 18
d3en.4xlarge 38
d3en.6xlarge 58
d3en.8xlarge 78
d3en.xlarge 10
f1.16xlarge 394
f1.2xlarge 58
f1.4xlarge 234
g2.2xlarge 58
g2.8xlarge 234
g3.16xlarge 737
g3.4xlarge 234
g3.8xlarge 234
g3s.xlarge 58
g4ad.16xlarge 234
g4ad.4xlarge 29
g4ad.8xlarge 58
g4dn.12xlarge 234
g4dn.16xlarge 58
g4dn.2xlarge 29
g4dn.4xlarge 29
g4dn.8xlarge 58
g4dn.metal 737
g4dn.xlarge 29
h1.16xlarge 737
h1.2xlarge 58
h1.4xlarge 234
h1.8xlarge 234
hs1.8xlarge 234
i2.2xlarge 58
i2.4xlarge 234
i2.8xlarge 234
i2.xlarge 58
i3.16xlarge 737
i3.2xlarge 58
i3.4xlarge 234
i3.8xlarge 234
i3.large 29
i3.metal 737
i3.xlarge 58
i3en.12xlarge 234
i3en.24xlarge 737
i3en.2xlarge 58
i3en.3xlarge 58
i3en.6xlarge 234
i3en.large 29
i3en.metal 737
i3en.xlarge 58
inf1.24xlarge 321
inf1.2xlarge 38
inf1.6xlarge 234
inf1.xlarge 38
m1.large 29
m1.medium 12
m1.small 8
m1.xlarge 58
m2.2xlarge 118
m2.4xlarge 234
m2.xlarge 58
m3.2xlarge 118
m3.large 29
m3.medium 12
m3.xlarge 58
m4.10xlarge 234
m4.16xlarge 234
m4.2xlarge 58
m4.4xlarge 234
m4.large 20
m4.xlarge 58
m5.12xlarge 234
m5.16xlarge 737
m5.24xlarge 737
m5.2xlarge 58
m5.4xlarge 234
m5.8xlarge 234
m5.large 29
m5.metal 737
m5.xlarge 58
m5a.12xlarge 234
m5a.16xlarge 737
m5a.24xlarge 737
m5a.2xlarge 58
m5a.4xlarge 234
m5a.8xlarge 234
m5a.large 29
m5a.xlarge 58
m5ad.12xlarge 234
m5ad.16xlarge 737
m5ad.24xlarge 737
m5ad.2xlarge 58
m5ad.4xlarge 234
m5ad.8xlarge 234
m5ad.large 29
m5ad.xlarge 58
m5d.12xlarge 234
m5d.16xlarge 737
m5d.24xlarge 737
m5d.2xlarge 58
m5d.4xlarge 234
m5d.8xlarge 234
m5d.large 29
m5d.metal 737
m5d.xlarge 58
m5dn.12xlarge 234
m5dn.16xlarge 737
m5dn.24xlarge 737
m5dn.2xlarge 58
m5dn.4xlarge 234
m5dn.8xlarge 234
m5dn.large 29
m5dn.xlarge 58
m5n.12xlarge 234
m5n.16xlarge 737
m5n.24xlarge 737
m5n.2xlarge 58
m5n.4xlarge 234
m5n.8xlarge 234
m5n.large 29
m5n.xlarge 58
m5zn.12xlarge 737
m5zn.2xlarge 58
m5zn.3xlarge 234
m5zn.6xlarge 234
m5zn.large 29
m5zn.metal 737
m5zn.xlarge 58
m6g.12xlarge 234
m6g.16xlarge 737
m6g.2xlarge 58
m6g.4xlarge 234
m6g.8xlarge 234
m6g.large 29
m6g.medium 8
m6g.metal 737
m6g.xlarge 58
m6gd.12xlarge 234
m6gd.16xlarge 737
m6gd.2xlarge 58
m6gd.4xlarge 234
m6gd.8xlarge 234
m6gd.large 29
m6gd.medium 8
m6gd.metal 737
m6gd.xlarge 58
mac1.metal 234
p2.16xlarge 234
p2.8xlarge 234
p2.xlarge 58
p3.16xlarge 234
p3.2xlarge 58
p3.8xlarge 234
p3dn.24xlarge 737
p4d.24xlarge 737
r3.2xlarge 58
r3.4xlarge 234
r3.8xlarge 234
r3.large 29
r3.xlarge 58
r4.16xlarge 737
r4.2xlarge 58
r4.4xlarge 234
r4.8xlarge 234
r4.large 29
r4.xlarge 58
r5.12xlarge 234
r5.16xlarge 737
r5.24xlarge 737
r5.2xlarge 58
r5.4xlarge 234
r5.8xlarge 234
r5.large 29
r5.metal 737
r5.xlarge 58
r5a.12xlarge 234
r5a.16xlarge 737
r5a.24xlarge 737
r5a.2xlarge 58
r5a.4xlarge 234
r5a.8xlarge 234
r5a.large 29
r5a.xlarge 58
r5ad.12xlarge 234
r5ad.16xlarge 737
r5ad.24xlarge 737
r5ad.2xlarge 58
r5ad.4xlarge 234
r5ad.8xlarge 234
r5ad.large 29
r5ad.xlarge 58
r5b.12xlarge 234
r5b.16xlarge 737
r5b.24xlarge 737
r5b.2xlarge 58
r5b.4xlarge 234
r5b.8xlarge 234
r5b.large 29
r5b.metal 737
r5b.xlarge 58
r5d.12xlarge 234
r5d.16xlarge 737
r5d.24xlarge 737
r5d.2xlarge 58
r5d.4xlarge 234
r5d.8xlarge 234
r5d.large 29
r5d.metal 737
r5d.xlarge 58
r5dn.12xlarge 234
r5dn.16xlarge 737
r5dn.24xlarge 737
r5dn.2xlarge 58
r5dn.4xlarge 234
r5dn.8xlarge 234
r5dn.large 29
r5dn.xlarge 58
r5n.12xlarge 234
r5n.16xlarge 737
r5n.24xlarge 737
r5n.2xlarge 58
r5n.4xlarge 234
r5n.8xlarge 234
r5n.large 29
r5n.xlarge 58
r6g.12xlarge 234
r6g.16xlarge 737
r6g.2xlarge 58
r6g.4xlarge 234
r6g.8xlarge 234
r6g.large 29
r6g.medium 8
r6g.metal 737
r6g.xlarge 58
r6gd.12xlarge 234
r6gd.16xlarge 737
r6gd.2xlarge 58
r6gd.4xlarge 234
r6gd.8xlarge 234
r6gd.large 29
r6gd.medium 8
r6gd.metal 737
r6gd.xlarge 58
t1.micro 4
t2.2xlarge 44
t2.large 35
t2.medium 17
t2.micro 4
t2.nano 4
t2.small 11
t2.xlarge 44
t3.2xlarge 58
t3.large 35
t3.medium 17
t3.micro 4
t3.nano 4
t3.small 11
t3.xlarge 58
t3a.2xlarge 58
t3a.large 35
t3a.medium 17
t3a.micro 4
t3a.nano 4
t3a.small 8
t3a.xlarge 58
t4g.2xlarge 58
t4g.large 35
t4g.medium 17
t4g.micro 4
t4g.nano 4
t4g.small 11
t4g.xlarge 58
u-12tb1.metal 147
u-18tb1.metal 737
u-24tb1.metal 737
u-6tb1.metal 147
u-9tb1.metal 147
x1.16xlarge 234
x1.32xlarge 234
x1e.16xlarge 234
x1e.2xlarge 58
x1e.32xlarge 234
x1e.4xlarge 58
x1e.8xlarge 58
x1e.xlarge 29
z1d.12xlarge 737
z1d.2xlarge 58
z1d.3xlarge 234
z1d.6xlarge 234
z1d.large 29
z1d.metal 737
z1d.xlarge 58