But Ambrose is hopeful the 61-year-old will be persuaded to stay at Selhurst Park.
"He's massively important to us. He's the one who keeps us afloat and he's done a fantastic job this year under the circumstances," said the midfielder.
"We knew about this game before all the speculation started, and all the lads and the manager are concentrating on the game.
"The players haven't spoken much about it because no one really knows what's going on. All we can do is take it as speculation and get on with our jobs."
Palace's cup run has provided some welcome relief in south London, with the club in administration and inside the Championship relegation zone.
They were just three minutes from knocking out Martin O'Neill's side in the first match before Stilian Petrov grabbed a controversial equaliser.
"We're in good spirits despite dropping into the relegation zone. It's the FA Cup and it's a massive tie," added Ambrose, whose stunning 35-yard free-kick had put Palace 2-1 up.
"They knew they were in a game at Selhurst and we are underdogs again but we like it like that. We've pulled off a lot of shocks this year and we are looking for another one.
"They are a good team. They are battling for fourth in Premier League and they deserve to be there. But we showed at Selhurst we have got enough to battle and compete with teams like that."
Administration brought with it the 10-point penalty which transformed Palace from play-off hopefuls to relegation battlers.
But despite dropping into the bottom three after Saturday's defeat by Coventry, Ambrose is confident they can avoid the drop into League One.
"I hope we don't go down, I'm sure we won't, I can't even think about that," he said.
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