The eight engines is a side effect of of how large the aircraft is vs how big the engines of the day were. they are basically business jet engines by modern standards.

During the recent engine replacement project using one full sized engine per boom instead of the twin small engine nacelle was seriously considered. So 4 engines instead of 8. I suspect the reason the twin nacelle was kept was that going to 4 engines required more engineering rework than they were happy with. It certainly would have improved the b-52's range and fuel efficiency.

Either way probably a net zero on the stealth consideration.

Fun fact: with the re-engine project the b-52 now has the same engines as the A-10.