Does lime survey have an access code limit? example it does with 50,000 people

With access code you are referring to tokens? Then the answer is no. There is no built in limit, but your server environment (e.g. database server) might have limits. But for tokens it should be possible to have a few million.

Reading your double post in portuguese:

With 50.000 participants your problem is not the maximum number of tokens possible, but rather how powerfull your server environment is. While 50.000 is not an extremely large number, you should probably avoid that all of these 50.000 access the research at the same time.