My best suggestion would be to contact a local PIT BULL rescue (not an all-breed if a Pit Bull rescue is available, as they will have the experience needed to properly screen applicants for this spicific breed, and also know exactly what to look for in potentially adoptable dogs).
Let the rescue know that he will be neutered at the current owner's expense, and will be upto date on vaccinations, flea, mite, and worm treated, and any other medical treatment taken care of. Rescues often suffer most in need of the money to cover these routine things taht are the owner's responsibility. If the current owner will provide the dog with these services, it will help the rescue be able to assist without draining their resourses.
Having him neutered is VERY important before he is rehomed. He will be bred otherwise, and that will in turn add to the homeless Pit Bull problem. (And it is a HUGE problem. Please do a search on www.petfinder.com
just to you a small idea of the numbers in need...)
He is a very beautiful dog. That puts him at great risk for falling into the WRONG hands... and him being unneutered increases those chances.
If you are unable to find a Pit Bull rescue that is capable of finding foster space for him, ask that rescue for a copy of their application and contracts, and for some suggestions on how to determine if someone interested is a good home. I am sure that the rescue would be more than happy to offer up their experiences to assist.
Obviously, the best outcome is if the current owners can alter their life in such a way that they can keep him with them (and have him neutered). That would be the best-case scenario for all involved....