Gardner also provided eight rebounds for the Golden Eagles (20-7, 11-4 Big East), who reeled off their 24th straight home win and stayed in the hunt for the conference title following a Saturday loss to Villanova.
Jamil Wilson contributed 12 points and seven assists in Marquette's victory.
The Orange (22-6, 10-5) got 20 points from C.J. Fair but it wasn't enough to prevent their second straight defeat, which put them two games behind conference-leading Georgetown.
James Southerland put in 15 points for Syracuse.