Is there a ratio of advertising income you can expect on YouTube based on views/subscribers? For example, for every 1000 subscribers how much ad revenue can you expect? Is there a ratio that works? What other ways can you earn revenue off your audience?
Not really. It depends on several factors: how engaged is your audience (how many of your videos do those subscribers watch?), where your videos are watched (US CPMs [the amount you make for every 1,000 views] can be several times of those outside the US), how many of your views are on mobile (a lower percentage of mobile videos are monetized), and how much of your inventory can YouTube sell (YouTube does not usually sell ads on 100% of your views).
Aside from advertising (which you split with YouTube), you can also make money through product sponsorships, product placement, show sponsorships (mention a product or wear a particular brand during your shows) - you usually don't have to split these earnings with YouTube.
I run a Multi Channel Network on YouTube since 2009. I'm YouTube Certified in Audience Growth and Digital Rights.
Feel free to contact me for more info.