Marquinhos' transfer to psg is not confirmed at all at the moment.
Remember that cavani was announced to be presented in paris for weeks before it finally happened and since then nasser himself said how it was hard to finalize this transfer. Till the very end it was hard. Cavani's presentation was 2 hours and a half late because of napoli's president.
It could have gone wrong, and actually napoli's president wished for it to happen (he twitted that he didnt want to sell cavani) since he wanted to keep cavani. The problem was that there was a clause and that the PSG paid for it. Napoli's president had to sell him once the clause was paid and of course, once the player was ok to be transfered, and only the PSG accepted to pay that clause.
So it's not done. There's no deal at the moment. Nothing official, and when some people said marquinhos was in Paris on wednesday, it was a lie.