Fill is a cousin of retired giant slalom racer and fellow Kastelruther Denise Karbon. After junior high school, he started working as an auto body mechanic while attending a vocational school, which he left after becoming more involved in alpine skiing competitions. His mother tongue is German but he is also fluent in Italian and English. His idol in everyday life is his uncle Norbert Rier, leader of the Kastelruther Spatzen (a well-known folk group, especially in German-speaking countries) who dedicated the song "Wiedermal a super Zeit" to Fill for his silver medal in super-G at the World Championships in Val-d'Isère in 2009.