There are teams in the league that draw ridiculous crowds, Atlanta averages 52k but have had over 70k a lot Seattle averages 40k. The new team in Nashville had almost 60k. There are a bunch of teams that average crowds of 20k+
2019 MLS Attendance - Soccer Stadium Digest
The TV ratings are still mediocre but the fans are showing up to actually watch the games. It's still a niche sport but the league gets better and better every season. Will it ever top the English, German and Spanish league? Not likely but as the years go on and the league keeps getting better and better it has a chance to be one of the better leagues in the world simply because it will offer the chance to play in the US/Canada vs playing in a lot of these other leagues in the world.