Gill knocked down 5-of-6 shots from the floor for the Tigers (18-15), who also received a game-high 23 points courtesy of Andrew Bock. Sama Taku chipped in 10 points for Pacific, which will advance to the semifinals to face an opponent that has yet to be determined.
Duda Sanadze paced San Diego (18-16) with 16 points off the bench. Christopher Anderson tallied 10 points and six assists, but it was not enough as the Toreros finished the contest just 2-of-20 from 3-point range.
The Tigers hit on 44.4 percent of their field goal attempts and outrebounded the visitors by a 19-15 margin in the opening period. San Diego went into the intermission trailing, 32-24, after being limited to 29.2 percent efficiency from the floor in the first half.
The Toreros heated up to shoot 43.3 percent from the field after the break, but missed all eight of their attempts from beyond the arc. Pacific extended its lead by converting 15-of-19 shots at the charity stripe over the final 20 minutes of action.
Johnny Dee, who entered the contest leading San Diego with 16.9 ppg, was held to just nine points on 2-of-7 shooting from the floor. Pacific finished 6- of-12 from beyond the arc and outrebounded the Toreros, 21-18.