The Reds, chasing victory over Hull next Saturday in a bid to climb out of the bottom three, took over 1,000 fans to Nottingham Forest on Saturday where they secured a crucial point in their fight for survival.
Flitcroft's side are second bottom, but level on points with Wolves and Peterborough, while clubs up to and including 14th-placed Ipswich could still feasibly be relegated with two games remaining.
"The way the fans have supported us has been magnificent," Flitcroft said after Saturday's goalless draw at the City Ground.
"I've said in the press before it's overwhelming at times.
"We're growing as a group and as a football club. The relationship between these players and fans is growing."
Hull will secure automatic promotion with victory at Oakwell with anything less ensuring their race with Watford for a top-two finish will go down to the final day.
Flitcroft added: "If the same fans come in (against Hull) and give us what they've given us - they've been incredible.
"They've become supporters of this group and me, Mick Mellon's and Martin Scott's management style.
"If we can get new supporters in and they can be part of it - brilliant."