Gelula was born on May 7, 1994 in Philadelphia, Pennsylvania, to Karen, an attorney, and Jonathan Gelula, who owns a private label wine Business. She was raised in Reform Judaism. She attended Lower Merion High School and recalls having a difficult time in high school, having been "very lonely, but very comfortable being alone," and showed up to school so infrequently that she was forced to either repeat her senior year or drop out. She ended up dropping out and moving to Los Angeles by herself at the age of seventeen.
Gelula follows a vegetarian lifestyle, which she attributes to "asking [her mother] what Turkey was made out of; the answer was revelatory." In 2011, she became vegan. She has said that she admires the work of Actress Laverne Cox and the show Adventure Time. Gelula resides in the Silver Lake neighborhood of Los Angeles, California. She also says that although she is usually typecast as the "bad influence", she has never been much of a drinker and did not begin smoking marijuana until age 19.
In 2016, Gelula made her acting debut as the lead Actress with a romantic drama film First Girl I Loved directed by Kerem Sanga. The film premiered at the 2016 Sundance Film Festival and won the audience award for Best Of NEXT. Gelula's performance in the film as Anne received rave reviews from various critics.