Olise collected an assist after just four minutes when Marc Guéhi turned home his early free-kick.
He then added a goal by striking past Ben Killip midway through the first-half, meaning he scored twice and assisted twice in 62 minutes of FA Cup football - including his contributions against Millwall.
The young winger earned Palace fans’ Man of the Match with 80% of the vote, beating debutant Tayo Adaramola (5%) and Marc Guéhi (2%) to the accolade.
After the game, manager Patrick Vieira said of Olise: “He’s playing with a lot of confidence at the moment. There’s no doubt about his talent; he’s a really special player. But there’s still a long way to go and a lot to learn.”