Poirier had two goals and two assists and extended his point streak to five games. During his run he's produced six goals and six assists and leads Gatineau with 70 points in 65 contests.
Hyka, who has six three-point games this season, scored once and set up three others for his first four-point outing.
Simon Tardif-Richard had a goal and two assists for the Olympiques (29-34-5), who came into action with just one win in their last 10 games, while Adam Chapman had a goal and an assist.
Simon Boudreau, Frank Schumacher, Vincent Arseneau and Peter Sakaris scored for the Cataractes (15-46-7), who dropped their fourth game in a row.
The Olympiques went 3 for 8 on the power play while the Cataractes scored once on six chances with the man advantage.
Elsewhere in the QMJHL, it was: Baie-Comeau 5, Drummondville 4; Chicoutimi 5, Victoriaviile 0; Rouyn-Noranda 4, Blainville-Boisbriand 1 and Sherbrooke 4, Val-d'Or 3.
At Shawinigan, Que., the Olympiques jumped out to a 4-0 lead before the Cataractes fought their way back to tie the game in the third period.
Poirier scored twice in 45 seconds to put Gatineau up 2-0 after 20 minutes of action.
Tardif-Richard made it a three-goal game 3:50 into the second and Hyka made it 4-0 at 6:04.
Sakaris finally got one back for Shawinigan at 11:14 and Schumacher made it 4-2 heading into the final period.
Arsenau brought the Cataractes within a goal 48 seconds into the third and Boudreau completed the four-goal comeback at 8:19.
Chapman put an end to Shawinigan's momentum with what turned out to be the winning goal at 9:30.
Drakkar 5 Voltigeurs 4
At Baie-Comeau, Que., Gabryel Paquin-Boudreau scored once and set up three more and Felix Girard had a goal and an assist as the Drakkar (44-19-5) snapped Drummondville's (38-26-4) three-game win streak.
Sagueneens 5 Tigres 0
At Chicoutimi, Que., Sebastien Sylvester had a hat trick, Samuel Roussy scored twice and Julio Billia made 23 saves as the Sagueneens (30-31-7) blanked Victoria (32-27-9), which dropped its third game in a row.
Huskies 4 Armada 1
At Rouyn-Noranda, Que., Nikita Kucherov had two goals and two assists and Alexandre Belenger only had to make 15 saves as the Huskies (40-24-4) earned their fifth straight victory by defeating Blainville-Boisbriand (41-19-8).
Phoenix 4 Foreurs 3
At Val-d'Or, Que., Michael McNamee, Steve Lebel and Alexandre Comtois all scored in the third period as Sherbrooke (21-38-9) came from behind to down the Foreurs (35-27-6), who are winless in six games.