Howard, from Coldwater, Ont., scored four in the seventh end to defeat Saskatoon's Steve Laycock 10-6.
Howard's big finish came after Laycock tied the game with three points in the sixth.
Gushue, from St. John's, N.L., scored in the eighth end to edge Switzerland's Sven Michel 7-6.
Michel had gone undefeated through to the semifinal and tied the game with two points in the seventh end before Gushue finished him off.
Howard made it to the semis with a 7-3 win over Edmonton's Kevin Martin, while Gushue beat Sweden's Oskar Eriksson 7-5 in his quarter-final.