Gushue, from St. John's N.L., came into the game as the skip with the most Brier wins of all time at 114, and he used that experience to capitalize on McEwen's mistakes.
Team Wild Card sits at 3-1 after the loss while Team Canada inches closer to a spot in the championship pool with four straight wins.
Alberta's Brendan Bottcher stole four points in the first half and a four-ender in the seventh to force Greg Smith of Newfoundland and Labrador to concede in eight ends with a 9-2 loss. Bottcher heads into Tuesday's morning draw tied with McEwen at 3-1. Smith dropped to 1-3.
Nova Scotia's Jamie Murphy was looking to avoid a two-loss day after falling 6-5 in the morning draw to Team Wild Card, while Jamie Koe of the Northwest Territories was trying to prevent his third straight loss in the round robin. Koe emerged with a 7-3 win. Both teams now have identical 2-2 records.
The clock was working against Murphy as his team tried to blank the ninth end but ended up giving Northwest Territories a steal of one.
Thomas Scoffin of the Yukon took command in the second half and pressured B.C's Sean Geall to concede 8-2 after nine ends. B.C. fell to 0-4 and Yukon improved its record to 1-3.
Earlier Monday, Manitoba's Reid Carruthers and Northern Ontario's Brad Jacobs remained undefeated and tied for first in Pool B.
Carruthers (4-0) and his Winnipeg rink held on for a 9-6 win over Quebec. Quebec skip Mike Fournier (1-3) read the ice quickly and made some crucial draws in the first half of the game, and pulled to within a point of Carruthers after getting a steal of one in the eighth end.
Carruthers responded with two in the ninth end before Fournier conceded in the 10th.
Jacobs kept pace with Carruthers with a 9-4 win over New Brunswick.
James Grattan (1-2) struggled in the first half, allowing Jacobs to steal one in the second and fifth ends, followed by and easy three in the seventh.
Ontario's John Epping (3-1) posted a 14-3 win over Nunavut's Dave St. Louis to keep the pressure on the Pool B leaders. Nunavut fell to 0-4 and was the first team to be eliminated from the championship pool.
In a must-win scenario for both teams, host Saskatchewan improved to 2-2 with a 7-6 extra-end win over P.E.I.
Charlottetown's Eddie MacKenzie took the lead in the third after a big double to score three. Saskatchewan skip Matt Dunstone started to show his frustration in the eighth after missing on the final rock, giving P.E.I a steal of one.
Saskatchewan third Steve Laycock's experience was on display at the Brandt Centre, helping to set up Dunstone for two in the ninth. MacKenzie had a chance to win it in the tenth but his final rock overcurled to push the game into an extra-end.
Dunstone was able to draw for one with the hammer in the extra end.
P.E.I. dropped to 1-3.