There is much you can do right with YouTube but there is also a lot of things you can do wrong! For instance all of my affiliate videos are on the same channel, if Google decided i violated their tos I would have to start all over but Google see the value I bring. I would suggest using different channels for different niches rather than having 1 channel or 1,000 channels.
One of my favorite ways to give content a boost is to run ads on Facebook targeting people with interests that are relevant to the content. It’s fairly low cost since you are offering a free piece of content. By targeting people with relevant interests to your content, you drive the right people to the content and into the top of your funnel. And if your content resonates with them, they’ll share, link, and engage with the content in ways that will help Google see its value.