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
