It is definitely less popular than it was pre-ES6, but it is still used.

I personally use it at work every day, plus I notice there are quite a few libraries (both open source and closed source) that are obviously compiled from coffeescript.

There is also work being done on a new version, CoffeeScript6, which will compile to ES6 and future ES standards. Check out the discussion at https://github.com/coffeescript6/discuss