First link is a 404 and second link is from 2017 and doesn't have the information I want which is how much money they are making from storefronts.
Their windows store buy page[0] (also from 2017) suggests they'd prefer you donate than buy.. so it's probably not a viable model.
[0]: https://krita.org/en/item/krita-available-from-the-windows-s...
Looks like $6000 from steam, or 10%, in ~2016