They are up to ~80 employees if I recall. However the YouTube ad revenue is just one component not including video sponsorships and their merch store.

Up to ~100 according to Linus's reply tweet:

https://twitter.com/linusgsebastian/status/16094698614949519...

They have around 100 employees and rent, I think, (at least) two warehouse spaces. They also seem to do work-for-hire production work, merch, and Floatplane on top of their YouTube content. I'm sure there are other revenue streams that aren't obvious besides those listed in addition to their YouTube AdSense only being a slice of their advertising revenue since they do in-video sponsored spots.

Source on employee count: https://twitter.com/linusgsebastian/status/16094698614949519...

They own three or four different warehouse spaces in the same complex. 4 units comprise the main studio + shop area, LTT Store has its own unit, Labs has a massive warehouse they're working on setting up, and I believe they still have the original Labs space they decided to not go with (or this is what became the LTT Store space). According to what Linus has said in the past, they own (not lease) all of these units.

They have other revenue streams. Sponsorships, YouTube Premium, Floatplane, their online store, affiliate links on YouTube and their forums to name some.

Yes its a small part of the pie. In their 2020 review it was about 20% of their revenue. Their lttstore.com creator warehouse stuff has gone crazy since then - they were talking about having 5-10m tied up just in inventory waiting to sell. So, yes.