Gelman was born in Saint Petersburg, Russia. During the 1920s, he worked as a still photographer in European motion picture studios, and became a distributor of French films. He arrived in Mexico just before the outbreak of World War II, and as a result of the conflict, found himself stranded there. In 1943, he became the third partner of Posa Films, along with Mario Moreno and Santiago Reachi Fayad. The company's prime asset was Moreno's comedic talent, and the three producers crafted and marketed the image of Cantinflas.
It was Gelman who proposed the recreation of European classics as a way to appeal to audiences outside Latin America. Los tres mosqueteros and Romeo y Julieta were produced during this period, and Los tres mosqueteros was selected to be screened at the first Cannes Film Festival in 1946. The endorsement of Charlie Chaplin had secured the feature's billing, but in the eyes of French critics, it failed to live up to Chaplin's proclamation that Moreno was the leading comic of the era. The French people, however, were not as hostile to "Cantinflas", seeing in him a Mexican version of their Fernandel. 1958 a rift between Gelman/Reachi concerned about some wrongdoing contracts with Columbia Pictures by Gelman and Moreno,allowed Gelman engineered the film's without Reachi as a Producer. dubbing into French over the objections of Reachi who advise him about the possible poor reception of Moreno's dialect to the Europeans. The imitative efforts at universalize failed to appeal to non-Spanish-speaking audiences.
Gelman stood beside Moreno throughout his career, accompanying during the filming of Around the World in 80 Days and to the Golden Globe Awards ceremony. When the three partners disbanded in 1960 over the creation of Pepe, As Reachi formed a new company named Posa Films Internacional, S.A. 1959, all assets of Posa Films, S.A and its obligations, was transferred to the new company (buy-out)1961. After Reachi retired as Producer, President and partner of Posa Films INTERNACIONAL S.A.(1963) Gelman had the opportunity to changed his status as a Manager to a new Producer of Cantinflas movies.(1964).
He and his wife Natasha were avid collectors of Mexican art, and became its patrons when they commissioned Diego Rivera to paint her portrait. Mexican painter Gunther Gerzso, a friend of Gelman, painted his portrait and gave it to him as a gift. Upon Mrs. Gelman's death in 1998, their collection was donated to the Metropolitan Museum of Art, and has since been exhibited at the Seattle Art Museum and New York City's Museo del Pueblo. A great part of their collection is also on exhibit in the newly founded museum "Muros" in Cuernavaca, following Natasha Gelman's wish.