So let's get the early stuff out of the way.
1) Yes, people still play it and many people never stopped. I hosted side events for EVO 2014-2018, Final Round 2015, Fall Classic 2014, Combo Breaker 2019, CEO 2019, and the monthly Discord tournaments that now get 5000-10000 looks on the regular on NYCFurby. CB2019 Top 4 alone has like 370,000 last I checked.
2) Yes, the PC version still works, and so does GFWL. Spectator mode is busted but the actual in-game holds up extremely well. It's better netcode than most of the AAA games right now being it's rollback. I live in Richmond VA and play a guy in France regularly and it's almost offline smooth most of the time. Download the final version of GFWL from the Microsoft website before you install SFxT and you should be good to go. You should also download the Xbox app from the Windows store and sign in with that, in case the first sign-in says there was an error connecting or something.
3) Yes, people still play on PSN.
4) No, people don't play much on XBL. It's pretty much barren now.
NOW THAT WE'VE GOTTEN THAT OUT OF THE WAY! WELCOME TO THE SFxT DISCUSSION!
Here are the basics:
https://drive.google.com/file/d/1aShrPvnqta3JKFZFMkdB65fmR4v7nLmt/view
Here is the completed Roster Overview made by myself, with contributions made from several others. If you're new to the game, or just looking for a new character to try out, this handy dandy overview goes into detail explaining what you can expect from each and every character, including general gameplans, strengths and weaknesses, and preferred team position. Give it a look
For those of you new to Street Fighter x Tekken, or new to fighting games as a whole, here is a playlist we put together to help you learn about the games various mechanics and fighting game fundamentals.
https://discord.gg/BGK6GTa
Here's a link to the Discord where we do most of our matchmaking. It's a very active discord most of the time, there's always someone willing to scratch the itch