Father of a 6 year old, he lives with his mother here in nj, no court order or child support involved yet.Recently she hit him I called DYFS and posted a court appointment seeking total custody of my son.She's also single and a illegal alien, I am legally married and legal resident ,my wife is a citizen... what are my chances?

No one can predict what a court will do. They are supposed to look out for the best interests of the child. Courts are still biased towards a child being reared by the mother.

If DYFS didn't remove the child after the investigation, your chances aren't great.

You have much better chances at getting court ordered visitation. I would start with that and maybe later eventually get full custody. As scott mentioned if DYFS didn't remove the child then you really can't use that as a reason to have him move in with you.