The Eastern Conference-leading Crew (10-3-9) are 6-0-2 since losing to FC Dallas (6-10-5) on June 20.
Marshall scored off a corner kick in the 10th minute. He outjumped Atiba Harris at the edge of the 6-yard box to take a feed from Robbie Rogers and put a header past goalkeeper Dario Sala. Gaven entered in the 75th minute and scored unassisted 12 minutes later with a shot from 17 yards.
William Hesmer had only one save for Columbus, but it preserved the 1-0 lead in the 72nd minute when he pushed a header from Jeff Cunningham over the crossbar.
Reigning league MVP Guillermo Barros Schelotto returned for the Crew after a hamstring strain kept him out four matches. Barros, second in the MLS with 10 goals, came on in the 90th minute to a standing ovation.