With New Sun's power set, it sounds like he could easily vaporize Superman. However, it's stated that regular Gambit defeated him? I haven't read those comics so I'd need someone to clarify. If so, Superman wins.
@raecinio: Regular Gambit defeated New Sun because Mr. Sinister Gave regular Gambit his full powers back for the fight and in return he defeated New Sun but after the battle his powers were restored to average Gambit.