API gateway has in-built functionality to perform authorization.
But the examples provided by awslabs have lambda hooked to API gateway, where lambda is authorizing as p
Solution 1 :
Create and Use Usage Plans with API Keys : In this method you can use API Keys to authenticate a user. follow this link : API Keys method
Solution 2 :
You can AWS Amazon Cognito service for authentication. It is same as OKTA service. Follow this link : Amazon Cognito