It's not cut and dry, really. Most kitties do stop spraying after getting neutered, but there are some that don't stop. It really depends on the kitty. He might for the week or two after he gets neutered, and then stop (sometimes it takes time for the hormones to completely leave the system). Most of the male kitties I've had stopped after getting neutered, but I did have one that continued after getting neutered. I used to have the theory that he just got used to spraying, and didn't want to stop, but since then I've read that sometimes one of the testicles doesn't descend, and they miss it. Though I don't really know the scientific reason for it, I know that it's not that common, so I don't think you really have much to be worried about. I've had over twenty cats in my life, and about ten of them were males, so one is really not a big number, all considered.
Just take him in, get him neutered, and wait to see what happens. I'm sure everything will turn out great.