Gerbe was selected by the Buffalo Sabres in the fifth round (No. 142) of the 2005 NHL Draft after two seasons with USA Hockey's National Team Development Program. He won a national championship with Boston College in 2008, the same year he was named a finalist for the Hobey Baker Award, given to the top college player, after he scored 35 goals and 68 points in 43 games. He was selected the Frozen Four Most Outstanding Player after scoring five goals in two games.
Gerbe left college after his junior season and signed an entry-level contract with the Sabres. He made his NHL debut against the Tampa Bay Lightning on Dec. 6, 2008 but played the majority of the season with Portland of the American Hockey League, where he was named the AHL's top rookie with 30 goals and 56 points in 57 games.