Although George Lucas' independent production company Lucasfilm had been around since 1971, The Empire Strikes Back represented a bold leap forward for this iconic company.
This wouldn't have been possible without the huge success of the company's first two films, American Graffiti and the first Star Wars. The resulting financial windfall allowed Lucas to do something unheard of in the film industry—bypass the traditional Hollywood system and fund his movies himself. Although production difficulties forced him to take some funding from 20th Century Fox near the end of development, Lucas retained full control and continued to build up Lucasfilm's coffers.
Because of this growth, Lucas was forced to focus on the business end of The Empire Strikes Back rather than the creative end. In particular, Lucas focused his effort on International Light & Magic (ILM), the company's special effects wing. The Empire Strikes Back continued Star Wars' streak of creating innovative special effects, and its release would further ILM's reputation as the most prodigious special effects studio of all-time. You know Pixar? They were originally a part of ILM.
Needless to say, this is hardly a typical set-up. Thanks to the success of his early films, Lucas wasn't merely poised to reap the massive financial benefits of The Empire Strikes Back, but also execute his vision with full creative control. You know, we might even say that it helped him build an empire.