From what I've seen, a lot of people on the internet seem to think that a game bred pitbull could kill a gray wolf. I personally think that is crazy. Wolves are stronger, have a more powerful bite, and are actually more aggressive.
I recently watched The Dog Whisperer, which was an episode about wolf-dogs, and this one guy had a Wolf/German Shepherd hybrid, and a huge English Mastiff, and they once got into a fight which resulted in $1200 worth of surgery for the mastiff. The wolf-dog looked to be about the size of a regular German Shepherd and like I said, the mastiff was huge, and very well built.
Compared to dogs, wolves have huge canines. They also have much greater stamina and are generally better fighters. What do wolves fight? Other wolves. What do pitbulls fight? Other dogs. Which sounds like tougher competition?
Just look at their teeth:
A pitbull fighting a wolf would be kind of like a human fighting a chimpanzee. Although maybe I am wrong.