Sorry you wont really know until the puppies are born, and even then some of them might look like the mother and you will not know until they grow up.
If the female had not yet ovulated (had all of her eggs released) then they were floating around in there looking for a dad. The mutt will be the dad of those puppies. If all of the eggs had already ovulated and been fertilized by the Pit male, you will only have purebred Pit puppies.
If you are selling these pups, you cannot ethically say they are definitely Pit. The only way to tell for sure is to do a DNA test on each puppy and make sure they have the dad´s DNA.