It's a guess...impossible to know what is meant exactly as I think he is using the phrase in a very personal way. However, this is what I think it makes most sense in the context.
https://en.wikipedia.org/wiki/Pai_gow
The name "pai gow" is loosely translated as "make nine" or "card nine". This reflects the fact that, with a few high-scoring exceptions, the best a hand can score is nine


So, "Pai Gow" might mean "lets' complete this work...= let's try and "make nine" or do the best we can (get the best hand we can)

So, maybe when Axel says
AXEL: Raise your hands, if you’ve got... hands"
and then "PAI-GOW!" he is making a pun/wordplay on hands of cards/dominoes and hands to dig with.

I note that Axel is willing to dig from the beginning (unlike Lukas) who isn't sure what's happening
LUKAS: Yeah, okay... I’m with you, Jesse, I just want to know what we’re getting into.\"

and again
AXEL says: PAI-GOW!

JESSIE: Anyone else have a better plan?
OLIVIA: Jesse’s talking to you, Lukas. ..(.i.e Lukas do YOU have a better plan?)

and again Axel says
PAI-GOW! Let’s get digging.

So, the last time he is actually trying to get everyone started on digging.

I believe the other answers don't make any sort of sense in the context.

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Note added at 1 day2 hrs (2015-10-28 10:00:45 GMT)
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I also discovered that in Pai gow poker where the player ahs two hands (one with 2 cards and the other with five) that
``Pai-gow'' is a hand with no pairs, such as Q J / K 7 8 6 2.
But I can't really see how that would fit in here (unless Axel is saying there are no pairs of hands to dig? Which seems unlikely)

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Note added at 4 days (2015-10-31 19:37:03 GMT) Post-grading
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Glad to have helped