Palace go into the showpiece event at Wembley as underdogs and hoping to win the first major trophy in the club's history.
Speculation has raged for months over the Dutchman's future with Jose Mourinho heavily linked as his replacement.
United legends like Paul Scholes have stuck the boot in on van Gaal's regime and style on more than one occasion this season.
That's despite Scholes' fellow legend Ryan Giggs being van Gaal's assistant.
'Let's be honest'
And Holloway has claimed on talkSPORT that van Gaal and Giggs' relationship is non-existent.
"I don't know what input he's (Giggs) actually got," Holloway told talkSPORT.
"I feel for him, he's had a taste of it (last season), with Fergie, he would have been the sort of natural successor to it all but... you know.
"They don't look like they get on, let's be honest.
"There is no chemistry between the two of them is there? We don't know that, but I'm saying it because that's the way it looks.
"It's (van Gaal's style) not going to be floating his (Giggs') boat."
Man United mismatch?
Pictures of the unassuming Giggs sat alongside van Gaal on the Manchester United bench certainly seem to suggest Holloway has a point.
While nobody except the pair can truly know what their relationship is like, some of the football United have played this season is a world away from that Giggs produced as a player.
An FA Cup win would go some way to giving a turbulent season a silver lining.
But there are bigger and more fundamental questions to be answered at Old Trafford this summer.