His plans are to give away $200 billion more over the next 20 years, which should deplete just about all of his fortune. Maybe Bernie Sanders thinks he know better what to do with Gates's money, but Sanders remains a politician and a bureaucrat, whereas Gates already has decades of experience actually being involved in his foundation's activities. He doesn't hold rallies. He goes out and gets his hands dirty. That sounds better to me than a bureaucrat who wants to confiscate and then decide what to do with what he has confiscated.
Anyone who tosses Gates and Buffett into the same pot with Bezos, Musk and Zuckerberg does not get to claim piety to me. Besides, as someone who faces 73% in income taxes because no one in Congress, including Bernie Sanders, will say a peep about enacting Residence-Based Taxation**, I don't take Congressional shouting about tax fairness seriously anyway. Every time the Democrats Abroad try to meet with members of Congress about it, they either "have no time," or, more honestly at least, say no. At 9 million strong--about the population of Virginia--you'd think someone in Congress might do something about it. The last one that really sounded like he would was Senator Russ Feingold of Wisconsin, who, unfortunately, got defeated trying to defend his Senate seat from (ugh!!) the despicable Ron Johnson, who probably thinks "abroad" is a 1930s slang term for "a woman."
**Every country on earth DOES recognize Residence-Based Taxation EXCEPT Eritrea and the USA,