From 2015 "Some unnamed person at Google reportedly said that the site is "roughly break-even." https://www.cbsnews.com/news/4-reasons-youtube-still-doesnt-... which in turn quotes https://www.wsj.com/articles/viewers-dont-add-up-to-profit-f...
From March this year (2024): "Analyst Michael Nathanson of MoffettNathanson estimates that YouTube TV will become profitable this year" https://www.newscaststudio.com/2024/03/29/youtube-tv-profit-...
Part of this could be because they pay out roughly 40-60% of the revenue to the content creators, that leaves Google / Youtube with half the revenue that they use to pay salaries, maintain infrastructure, including storage, hosting and serving content.