My native language isn't English. Can you help me?
Most Helpful Guy
Both are correct.
By saying " I'm a fan of his" you're rather referring to the fact that you are one of his many fans, and it implies that you are part of his fan community (if you can go so far)
By saying "I'm a fan of him", you just say that you are a fan and that's it. It also implies that you "like" him".1