I don't know about in-depth, but a cursory google search brings up plenty of results regarding animator wages[1,2]. If you want to know more about how the industry operates, not so much salaries but how production works, working conditions, who's responsible for what, etc, then I highly recommend that you watch the anime Shirobako. It's an anime about anime production, and it's both very informative and simply very good in terms of storytelling, humor, etc.
[1] https://www.animenewsnetwork.com/news/2005-11-02/animator's-...
[2] https://80.lv/articles/how-much-do-japanese-animators-make/