>>3798966 (lb)
Sure they can. The other justices hear the case and rule. Her input is not considered. Just before Scalia uh…"passed" he had heard and written on the California teacher union case. When the case dropped, it was ruled 4-4, so lower court ruling stood, Scalia's position was removed. It had to be re-heard later.
You don't need 9 for the Court to proceed.