Kporha - who has starred for the Under-21s and made his debut as a substitute against Fulham last month - replaces the suspended Daniel Munoz at right wing-back, alongside Marc Guehi, Maxence Lacroix, Tyrick Mitchell, and Trevoh Chalobah, who scored against Brighton on Sunday.
Fellow Academy graduate Justin Devenny is among the substitutes, with the Eagles hoping the front three of Jean-Philippe Mateta, Ebere Eze and Ismaila Sarr can see them over the line.
Victory would mean a first League Cup semi-final since 2012, when Darren Ambrose scored a remarkable winner at Old Trafford in the quarters.
Arsenal make eight changes to the side which started the weekend's 0-0 draw with Everton, with Thomas Partey, Jakub Kiwior, Jorginho, Ethan Nwaneri, Raheem Sterling, Leandro Trossard and Gabriel Jesus also coming into the side alongside Kieran Tierney, who is playing for the first time since August 2023.
Arsenal: Raya (GK), Partey, Timber, Kiwior, Tierney, Jorginho, Merino, Nwaneri, Sterling, Trossard, Jesus.
Subs: Setford (GK), Saliba, Gabriel, Kacurri, Lewis-Skelly, Odegaard, Saka, Martinelli, Havertz
Palace: Henderson (GK), Kporha, Chalobah, Lacroix, Guehi, Mitchell, Lerma, Hughes, Eze, Sarr, Mateta.
Subs: Turner (GK), Clyne, Ward, Richards, Doucoure, Schlupp, Devenny, Kamada, Nketiah.