Sieg is the No. 5-ranked player in the Keystone State and is the No. 17-ranked safety in the nation.
James Franklin said Monday that Allar and Dennis-Sutton would be game-time decisions.
"We've got to step up to the challenge. That's what we're here for, and that's what we're going to do."
Penn State hasn't lost a Big Ten regular season game since November 5, 2023.
The front boasts the eight-best rushing defense in that nation and has only allowed more than 100 yards twice this season.
Oregon remained No. 1 after its 38-9 dismantling of Illinois, and Georgia stayed at No. 2 despite being on a bye.