Abortion wasn't outlawed at a federal level. No "minority" is deciding that abortion should be illegal. The only places where abortion becomes illegal is states where the majority has voted for it, democratically. That's the opposite, the tyranny of the majority. Which is what exists in any democracy when it concerns rights which can be restricted by a majority of voters without being protected at a constitutional level- which abortion never actually was.
And as per your own graph, a majority of people support restrictions on abortion.

So what is to stop an ammendment?

Democracy lul

How many votes would biden need?

You keep thinking that this is about abortion or gun rights. It's not.
What the Supreme Court has done is to correct gross errors in rulings of the past.

It doesn't matter what those past rulings were about. It only matters that they were arrived at, without regard to Constitutional Law.