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