Seton Hall (4-0) used a 17-point run midway through the first half, including a pair of 3-pointers by Gibbs, to turn a 4-point lead into a 41-27 advantage at the half.
Illinois State trimmed the lead to seven with 12:04 left after a 12-5 run, but Seton Hall called timeout and Gibbs nailed a pair of treys out of the break to push the lead back into double-digits. The Cardinals (2-2) got it to 5 with 44 seconds left, but Gibbs made four straight free throws to ice it.
Isaiah Whitehead had 18 points and six assists for the Pirates, who hit 12 of 18 (67 percent) from beyond the arc.
Bobby Hunter paced Illinois State with 23 points, including 4 of 7 on 3-pointers.