The hosts went down by three wickets in the second ODI Sunday at the Sir Vivian Richards Stadium, two days after scoring an exciting 13-run victory in the first game of the three-match series, reports CMC.
"We're building towards the 2015 World Cup and we've got to look at this game as such. This could be the World Cup final for us so we've to get our 'final faces' on... and come out Wednesday and approach it in that way," Gibson said.
"We're one game away from winning a series against a team ranked higher than us, which is a good achievement, so there's all to play for and hopefully the guys are up for it Wednesday."
West Indies were always up against it Sunday after they were dismissed for 159 off 44.2 overs, after being sent in by England. Only Lendl Simmons with a top score of 70 got past 20, as the West Indies batting struggled for the second straight game.
Simmons' half-century followed up his 65 in Friday's first ODI and Gibson singled him out for praise.
"He has played very well. He's done the job and it has always been sort of a restoration job trying to repair the damage that's been done at the top," Gibson noted.
"He usually opens but is batting in the middle order and he's really holding the innings up as he showed in the last two games. They've been two really good innings. He will look at it and think he could've turned one of those fifties into a hundred, and that would have given us 220 runs (in the second ODI) and the story would have been different.
"I'm really pleased with how he's playing and hopefully that form continues through the next match and into the T20s."
West Indies scented victory when they reduced England to 105 for seven thanks to two-wicket hauls from left-arm spinner Nikita Miller and seamer Dwayne Bravo.
Off-spinner Sunil Narine was brilliant, conceding just 25 runs from his 10 overs and grabbing the vital wicket of Luke Wright, but the experience of Ravi Bopara (38 not out) and captain Stuart Broad (28 not out) saw the visitors home.
"A score of 160 was never really going to be enough but the guys fought really hard. It was a gallant effort to try and defend such a small total and to get them seven (wickets) down," said Gibson.
"Even then we had a couple of chances to get Broad out and that would have changed the game and tilted it in our favour but that wasn't to be. The way guys fought was pleasing.