It did well in the State of JS, but there are no big names using it. I think it will have grow in popularity in 2020. The community is still relatively small.

The list of "who is" is most certainly growing, and there are definitely some bigger names out there: https://github.com/sveltejs/svelte/blob/master/site/src/rout...

Jobs listings are cropping up in sundry places too. See for example: https://sveltejobs.dev/jobs/apple-senior-front-end-developer

It seems to have PR traction (no snark intended), it keeps popping up on here, so some people must like it.