Botvinnik was sometimes accused of "over preparing" before initiating attacks against the opponent. In this case, white's piece coordination and local piece superiority on the kingside combine to enable a truly beautiful sacrificial attack.
Very strong sacrifices and the enduring of so many checks. You have to be a true master to get this calculated in advance. Or Botvinnik was just a bit adventurous on this very day? :D
Interesting thought! It looks like then White would play fxg6, with a double attack on the knight. If the knight moves away, White can harass the Black king away from his rook and pick it up. Play around with it--lots of possibilities.