More exactly is, that the yellow card will expire after the QF. So no matter if he plays in the round of 16 or not, if he earns another one in the QF he will miss the semi-final.
It's the same in every FIFA/UEFA competition. Otherwise all 22 players would have a "free" yellow card for the quarter final and this would turn these matches into pure hacking.
So if we happen to get past Slovakia. We will have to play a foul free game to make it to the SF unscathed.. Especially to a team like Italy possibly? Very tough to do
Every tournament this fact has to be repeated. You would think that by now the regular posters here would remember this.