Final answer:
Universal Studios was the studio that played a crucial role in the launch of Steven Spielberg's film career, particularly with his work on the television film 'Duel' and his feature debut 'The Sugarland Express,' which subsequently led to his breakthrough with 'Jaws'.
Step-by-step explanation:
The studio that was influential in starting Steven Spielberg's film career was Universal Studios. Spielberg's directorial debut for the cinema was with the film The Sugarland Express in 1974, but even before this he had directed the television film Duel in 1971 for Universal Television, which brought him to the attention of the executives at Universal Studios. His early work impressed the studio executives, and they offered him a long-term deal, making him the youngest director ever to be signed for a long-term deal with a major Hollywood studio at that time. His subsequent project, Jaws (1975), also with Universal Studios, cemented his reputation as a leading director in the film industry.