Lewis was 8 of 11 from the field and grabbed 11 boards while Dantrell was 10 of 13 for the Colonels (7-15, 3-7 Southland Conference).
Lewis also sank a game-high seven free throws.
Nicholls State trailed 22-21 midway through the first half before Sam McBeath hit a 3-pointer to put the Colonels ahead 24-22. From there, the Colonels used a 12-1 run to jump ahead 36-23 with 4:50 left in the first half.
The Colonels opened the second half with an 11-5 run, taking the lead for good, 55-40, behind a 3-pointer from Dantrell.
Nicholls State (8-14, 1-8) shot 61.5 percent (32 of 52) from the field, outrebounded the Bobcats 34-25, and forced 18 turnovers.
Brooks Ybarra led Texas State with 23 points.