That Chinese counterfeit jersey is of horrendous quality. It's got threads sticking out and the #7 looks like it's patched together from two strips of white fabric instead of one continuous swath.
So to answer your question: If the jersey is fake, the signature certainly is as well.
The jersey is a custom just like any other Nfl jersey besides on field jerseys. Now if someone could tell me about the Autograph that would be awesome.