Gaining youtube subscribers from facebook ads?

[Imsillyokays]

Let's start off on youtube.
Make sure your videos have a clear correctly spelled title (this allows it to come up on search). Additional tags can also be added, to go into more detail, so you can say what highlights there are in the video etc. so your video will come up in a search for those tags, so if you put 'xbox' in the tags, when someone searched/watched another video with the 'xbox' tag in theirs, your video will be related if it has similar enough tags (and you need to make the thumbnail interesting).
Now to facebook.
With the page & Ad -
Make sure you give enough information, but keep it short so people don't get bored. If your page has enough similarity to other youtube pages, facebook will automatically put it there as a 'like' suggestion.
It costs money to make an add, but it's worth it if that's what you want. If peoples likes are as similar to your page, it will be in their page/ad suggestions.
(you could also promote yourself here to get started, I'm sure people wouldn't mind)

Hope this helped c: