Many, many videos, patreon, streaming, sponsors, etc.

That's why they always tell you to SMASH that like and subscribe button

Sponsorship can easily get you a good 4 digit deal per video. Even for small-ish creators. 5 digits if you regularly get million plus views

Patreon is the other big one

Fun fact: yt premium views pay orders of magnitude more per view. In a world where a large percentage of viewers have premium, there would be almost no incentive for most small and medium sized channels to have sponsors in videos

In addition to what others have said, the value per million views changes depending on how profitable your audience is. Education is notoriously low, something like makeup is much higher.

For a lot of creators it may not even be about the money they earn directly from it. I have a small educational YouTube channel. It brings in about 20 bucks per month in ad revenue, more in the past when I was more active. But really it's a nice feather in my cap and something neat on my resume. A modest YouTube channel won't pay enough by itself to make the effort worthwhile. But if that channel gets you over the top on a new high paying job? Then it's worth it. In this context, a YouTube channel functions as a kind of personal brand/promotional material.

A lot of content creators post on multiple platforms as well, other than PH that is.

they have brand deals, promotions, sponsors and patreon. a asian ones i used to followed had to use these to stay alive they barely make 2million views per video. youtube does all sorts of stuff to your algorithim which can exclude you from reach other peoples feeds or not all. the big ones certain are using these+ they are already wealthy and expands to have thier own company which contributes more.

some are quite small and only upload occasionally and dont sustain themselves on youtube at all, mostly the ones about sciences as many of them are burgeoning scientists, going to school,,,etc.

Sponsors will pay 5 figures for a 30-second promotional segment of the video.

Nebula, Patreon, merch…

Didn't you read the article? They cross post their videos to pornhub.

Not everyone earns the same amount of money per view. If you're making niche content for more wealthy individuals, you'll get more per view, from what I recall

They sell their bath water

ad revenue