The correct spelling is Jacques.
It is spelled Jacquez on programs and such because announcers and such were not pronouncing his name right (They pronounced it Jah-Kweese or Jah-Kwess instead of Jah-Kwez). So, the coaches and school had it switched to Jacquez in public settings.
Basically, if you look at Jacques's birth certificate or driver's license, it will say Jacques. But, if you see it on Rivals or a player profile, it will say Jacquez.
Either are acceptable, and technically both spellings are accurate.