The acclaimed filmmaker Steven Spielberg has struck a multiyear deal to make movies for Netflix Inc., a massive get for the streaming behemoth as it faces increased competition for talent and content from bulging purse rivals such as Walt Disney Co. and Amazon.com Inc.Under the terms of the deal, revealed on Monday by Netflix and Mr. Spielberg’s Amblin Partners, the studio will make multiple new movies for Netflix over the course of the agreement. The pact with Netflix doesn’t affect Mr. Spielberg’s long-term relationship with Comcast Corp.’s Universal Pictures where Amblin Partners is situated.Netflix’s signing of Mr. Spielberg, whose output consists of “Jaws,” “E.T.,” and “Saving Private Ryan,” shows that the company is keeping a keen eye in its rear-view mirror. Although Netflix is far and away from the most popular streaming service with 208 million members around the world, its competitors are growing in number and strength.Walt Disney’s Disney+ has made solid inroads in the US and abroad. Other rivals are also gunning for Netflix. Last month, Amazon acquired the MGM movie and TV studio in a deal valued at $8.45 billion including debt. Among the properties that will now be part of Amazon is the James Bond franchise.