Early response to Biden’s State of the Union address indicates that in the immediate term he has stabilized the floor of his support among his 2020 voters. In other words, his speech has helped his campaign stop the bleeding (for whatever bleeding their was).
I would say that his State of the Union address did the above to the point where he won’t, indeed, need 80 million votes again. See this other P&E thread for further discussion of numbers apart from the State of the Union’s affect upon them.