Actor and comedian Josh Gad may be known best as the voice of Olaf the snowman in the two biggest animated movies in the history of Hollywood: Frozen and Frozen 2. But Gad originally rose to fame on Broadway, earning a Tony nomination for his role in the hit musical “The Book of Mormon.” In this week’s “Sunday Sitdown,” Willie Geist gets together with Gad at his favorite bar in the theater district to talk about his journey from that show to his latest project, an HBO series called Avenue 5 set in outer space.