To be honest I don't think an invasion of Poland is on the top of Putin's agenda. I also don't think he necessarily wants to destroy NATO from an ideological standpoint. But I do believe that he's an opportunist - if he sees NATO struggle & has sympathetic local support within smaller Eastern European nations like Latvia, Estonia etc then I wouldn't be surprised if pro-Russian rebel groups, supported directly by Russia special forces, begin to cause trouble.
The whole NATO vs Russia situation has been done a lot on more military minded forums than this one. I think there's always going to be some kind of bias - those in the West are more likely to believe NATO will win while the Russians believe they would.
Then you get some individuals & arms manufacturers coming at it from a slightly different direction. IE Russia are too strong for us currently but buy our latest jet fighter & missile system so they wouldn't be.
There's so much claim & counter-claim & add that into the fact that governments deliberately don't reveal the full capabilities of their weapon systems makes it hard to judge.
Generally speaking, Western technology is further advanced in most areas. The Russians still haven't fielded a single stealth aircraft operationally unlike the USAF managed who to do in the 80s & 90s with the F-117.
The F-22 has been in use for around 10yrs now while the PAK FA is still in development. The EF2000 Typhoon should be superior to the Su-35 Flanker but until it gets the Meteor missile then it'd bet it'd be a relatively close fight (I've heard that the latest generation of Russian ECM is rather effective against AMRAAM missiles) if the pilots have the same ability & training.
However, it's well known that Russian pilots don't get anywhere near as much training as their Western equivalents & NATO nations have state of the art simulators so training sorties can be flown in those instead.
I don't think the Russian integrated air defence vs VLO aircraft, missiles & low level flying tactics will ever be proven one way or the other in theory. There's no doubt the S-400 systems are highly regarded &, from what I've read, the Russians deploy Pantsir-S1 & similar systems to defend the S-400 SAMs from anti radiation missiles.
But going up against these formidable systems are stealth platforms like the F-22 carrying Small Diameter Bombs internally & flying at very low level with stand-off ECM aircraft & possibly UAVs diverting the attention of the SAMs to make it even harder for the Russians to detect.
If the Russia IAD is breached, even if only temporarily, it opens up a corridor for non-steath aircraft like the Tornado GR4s to fly in & volley fire Brimstone missiles against Russian tanks. The new T-14 tank is meant to be a beast but it isn't in service yet. & although it has anti missile defence system there's a good chance multiple anti tank missiles will get through, especially if volley fired.
It does come down to whether or not NATO would defend Eastern European countries against Russian aggression. Some may not have the stomach for it.