I see the X1X helping overall very little, but selling to the most hardcore Xbox fans who already own an X1 (who probably already bought X1 w/Kinect at $500 on launch, and then X1S lol).
PUBG is .. probably not a big factor to be honest. The sooner they release it, the better chance of any impact. If it was already out on Xbox it would get some traction. But it's about to be the usual fall rush of mega IPs, already starting with Destiny 2, and the PUBG community is already really well entrenched on PC, where a game like PUBG can thrive decently. It should be a $20-$30 game. There is very little content, it's super janky, it looks like a 2008-era game in almost every aspect other than player count, and that's being VERY generous. I mean, it's a pretty hideous game to look at. There's also the matter of the thing even running on consoles in a respectable way. It's telling we still don't really have console footage to go on, it's notable for being pretty CPU heavy, and runs like trash even on pretty pricey PCs with good CPUs. With low level CPUs it's just an abomination.
If it comes out rushed at 30fps with drops on X1X, and is virtually unplayable on stock X1/X1S, that will pretty much seal the game on console. It certainly won't run any better on PS4/PS4P.