Koscielny has an ankle injury and Gervinho is suffering from a mild muscle strain while Walcott limped out of Saturday's win over Bolton with a knee problem.
However all three could be fit for Sunday's North London derby against Tottenham Hotspur in the Premier League.
“Touch wood we can absorb the number of games we face well, and we have some younger players pushing like Coquelin and Frimpong, who are playing very well,” he told the club's official website. “So hopefully we can cope with it.
“If Abou Diaby comes back well and quickly we should, number-wise and quality-wise, be all right. That depends as well on the injuries we have in the next two or three months.”
Wenger added that the long-term absence of Wilshere, who has undergone ankle surgery, should not affect the club's season. The Frenchman recently brought in quality playmakers in the form of Benayoun and Mikel Arteta.
“[Jack’s injury] makes us a bit shorter in midfield and it puts a bit more pressure on our midfielders to perform game-in, game-out, because we will have less rotation possibilities,” he said.
“But every club can be tested on that front so it shouldn't impact our end result of the season and shouldn't be any excuse at all. Jack can come back and be very strong and help us finish the season well.”
Arsenal drew their opening Champions League Group F match against Borussia Dortmund 1-1 and lie 13th in the Premier League after a disappointing start to the season.