The Evita homage is at the beginning of act 2, in the scene with the song "Thank Goodness". It is the engagement celebration. Glinda, when in front of the crowd, lifts her arms out to side in a slightly upward position, much like Evita does when addressing the massive crowd outside the Casa Rosada. Both are public figures who use rhetoric and an "I am like you and care about you" attitude to compel the masses, who "worship" them.
"Why do you care what people might say? Why try to fit into their design?" (Side Show)