This site is interesting, by their estimation, that could be way off,
DTube currently worth $868,000
https://www.worthofweb.com/website-value/d.tube/
Steemit $97,000,000
https://www.worthofweb.com/website-value/steemit.com/
YouTube $102,650,332,250
https://www.worthofweb.com/website-value/youtube.com/
I do think Steemit could be worth $1T in the future but there's a long way to go just to catch up with YouTube. Hopefully the masses will see the advantages of Steemit and DTube over the traditional sites.