He didn't hit 2k. He got close and stopped but as far as I can tell he grinded puzzles really really hard and got really comfortable with a certain set of positions he was able to constantly force. Really amazing achievement.
How did tyler get 2k?

he stopped for the moment, because he has child and he wants to stream more, but he will surely be playing some time again. He did a break once too

He hasn't played for about a month. To answer your question though, his success comes from a few different areas.
Firstly, let's cover his opening, The Cow. While not being a particularly good opening, he plays it EVERY game in BOTH colors. It's very similar to one tricking a character in any game. If you learn the ins and out of your system (opening, character etc.) you're going to be prepared for anything. Using a website like opening tree helps you to visualize this.
Secondly, his grinding ability. The ability to sit down and do a ton of puzzles in one sitting or play a ton of games in a row is definitely a useful one to have. Specifically, the puzzles build the pattern recognition needed for the middle game. It takes a special kind of person to grind out the 6000 games of rapid Tyler has played since starting.
There's a ton of videos out there from that talk about his unique approach to the game and how you can maybe learn from him in the long run.

This is my opinion about way he get to almos 2k:
1 - Puzzles: doing +12,000 puzzles is not for everyone.
2 - The COW: using an opening that is not very well known, while at the same time allowing him to play the same opening with the white or black pieces, an opening that allows him to develop his pieces quickly, in a passive but safe way.
3 - Playing defensively: using the COW he basically waits for his opponent's moves, reacting as the game develops, his opponent on the other hand spends more time thinking about how to play and in the end ends up losing either by time or blunder.
It comes down to his position in life. He built a successful business revolving around video games, and has a large audience and fanbase, he's achieved a lot and not to mention having a perfectly matching wife. When you are in a good place in life such as him, you have a lot of time to spend and you do not have to worry about much, all your needs and securities are covered from the successes. This allows you to sit down and play chess for hours on end, developing immense skills and knowledge faster than the average person, also he's definitely intelligent so that helps.
What has he done throughout his chess career to achieve this in a short amount of time? I see the volume of puzzles and games he does at least 20 puzzles and games a day since his account creation?