For the UC’s and CSU’s, they are FASFA only schools so the FA forms would have to filed again if he takes a Gap year.
Regarding deferrals:
The UC’s and CSU’s normally do not allow deferrals but due to Covid this year, some campuses have allowed students to defer.
Each school has their own policies about applying to other schools after the student defers, so that would have be investigated upon receiving an acceptance. In general, if the school does not allow a student to apply to other colleges after the deferral/Gap year, then the student must withdraw their acceptance to pursue other schools.