Hi @moyix!
I believe the set_seed() method being called is for the random processes that happen inside the Trainer class that is used for training and finetuning HF models. So, naively, I would say that calling set_seed() to generate different output from the nominal GPT2 won’t work.
Unfortunately, I can’t think of a way to do this. Here 13 is an article by @patrickvonplaten about generating text with different decoder methods that might be useful. Otherwise, maybe @sgugger can provide some insight?