The Canadians will meet Mexico in the semifinal round on Thursday.
Hoilett opened the scoring in the 18th minute when he received an assist from Eustaquio and placed a shot from the center of the box into the bottom left corner of the net.
During the 68th minute, Hoilett had his back-heel touch in the box carom off the shins of two different Costa Rican defenders and land perfectly in front of Eustaquio, who buried a shot between keeper Esteban Alvarado's legs to double the margin.
Costa Rica failed to put a shot on goal. Alvarado made three saves.
It is Canada's first time reaching the Gold Cup semifinals since 2007. The country last won the tournament in 2000.