Pep Guardiola's City have scored 16 goals in their last five matches heading into Saturday's game against Mikel Arteta's Arsenal.
City have netted at least three goals in each of their last three meetings against the north London side and Walker, 30, is confident the streak will not be broken at Wembley.
"It's a knockout game, it's what both teams do in both boxes that makes the difference," Walker told City's website. "I think we have proven that when we're on fire and things go our way, we can go and score three, four... and maybe even seven or eight.
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"Hopefully, we can do that against Arsenal. We know Mikel knows how we play. It will be difficult to break them down and they've got good players in good areas. But I think on our day we can beat anyone."
Walker hinted that City's substitutes will have a major role to play as they continue their quest for a second successive FA Cup triumph.
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"With this squad, it's not just the players who are starting, but coming off the bench. They can make the difference if you've run for 70 minutes and you're defending balls and onslaughts of attacks," the England defender said.
"It's great for us to have. It's not just about the 11 that start, it's about those on the bench and whoever the manager brings on."