Not the poster, but maybe I can help.

Your comment is a little unclear, so it‘s hard to parse your exact question. But it seems you are conflating 3 things, PyTorch, RL and Gym/Training (?).

– PyTorch is a framework which lets you define neural network models.

– RL is a collection of methods to train neural networks (change the network parameters to improve its performance).

– An RL-Gym is a framework to apply the neural networks to some problem. This lets you collect the data necessary to later use the methods of RL to train your model.