PSG need a win to guarantee their own progress but will also be through if Liverpool fail to beat Napoli.
Although Napoli are second in the Serie A table having won four of their last five games, they are already eight points behind leaders Juventus, who are hunting an eighth consecutive title.
But De Laurentiis will keep faith in Ancelotti, who previously said Napoli would be "a*******s" if they fail to finish in the top two in Group C.
"Going out of the Champions League or continuing does not change anything, for me this year’s big signing remains Ancelotti," the club president, also a film producer, said on Radio Kiss Kiss.
"I am happy to have found a partner like I did in film. We've been in Europe for nine years. You know I am always thinking differently about football.
"We are out at sea, it's our natural element, and for the Neapolitans it's important, we hope it's a good omen. I never look back, that's my philosophy: always think about tomorrow."