Depends.
I subscribe to Deep South Homestead. Danny King's channel is mostly about gardening, farm animals, food preservation, etc., and has about 210,000 subscribers. He's most likely making $1600-$2000/month from YouTube. He's also making money from Patreon.
That's not a great living, but he's retired and the channel allows him to plug any other business ventures he has, along with picking up some freebies to test. Things like garden seed or a manual weeder (Hoss Tools).
Since I've been following him, he's built an off-grid cabin, two hoop houses, a farm pond, bought two small new tractors, reworked some of his barn and bought some Dexter cattle. Looks like he's plowed all his YouTube profits back into his place and increased its value.
Another guy I subscribe to, does videos on tanks and other modern armor, modern being WW1 on up to present. His day job is with a video game company, but he's also an officer ( light bird, I think)in the National Guard. He puts out less videos than Danny, but his views are about double, so his money is about double. And he's used his channel to flog a book he wrote on tank destroyers, along with cementing him as an authority on many things armor, especially WW2.
So a YouTube channel can help a person create their own brand or niche, besides making a bit of side money.