I don’t think there is a set number, it looks like a crapshoot. My DD got accepted with a 2250 SAT including a 720 M, top 1% and NMF. She is a varsity athlete which might have helped. I saw an Asian male that had a 2290, top 2% and many math ECs that did not get CS. I also saw a white male, SAT 1990 and a varsity athlete that did get CS.
I do know, if he can get a perfect score in math that will help. The other scores do not seen to be nearly as important. Essays may be important. His best bet is to get his math score as high as possible.