Time, effort, content, marketing, networking, advertising...
What exactly are you looking for, here? There's no fast and easy way to achieve this unless you're a pre-established brand or celebrity. Do some bloody research, mate. Google is your friend. For now.
Also- it's better not to approach it from the angle of "man, this long-established yt channel is blowing everyone out of the water and I wanna compete with them." That's going to destroy you. Focus on what you enjoy and what you can offer. Or find a different hustle, if you're as desperate and clueless as your words make you out to be.