*to me* he looks like some sort of Am Bully mix? But he could just be a fat pit mix.. but like brindle said, we cant tell you the breed or bloodline. without papers youll never know for sure.
It's a mutt. To me, I don't see any Pit Bull in there... but anything short coated with a not-narrow head is going to get labeled as a pit mix. It looks like a lab/hound mix to me - though doubtful either parents were purebred anything.