Here we go again. No sources.
According to his site:
https://www.sanders.senate.gov/press-releases/sanders-make-college-tuition-free/
It would cost $70B/year.
According to this site, he makes about $9.8B/year, so even a 100% tax wouldn't do it.
The problem is how do you calculate his taxes? He's already doing that and paying his $800 or whatever it is. So you have to make assumptions about how much you would tax at 4.7%.
I therefore assumed this meant if his entire net worth were taxed at 4.7%.
According to here which tracks it real time: https://www.forbes.com/profile/jeff-bezos/
It's currently $270B.
$270B x 0.047 = $12.7B.
So no, you couldn't fund it just by taxing him 4.7%. I think we'll need to create a special tax on billionaires to cover the rest.