I didn't know Gil Cates personally—I think I must have met him at least once during my time on the L.A. theater scene, and one of Back Stage West's best Garland awards shows (hosted by Chris Wells, with performances from Medea/Macbeth/Cinderella, Reefer Madness, Pacific Overtures, the presence of Carol Burnett) did take place at his lovely Westwood theater.
But Cates did loom over the L.A. theater scene in the best possible way, and what was especially striking about him was that he was the only theater leader in that "industry town" who kept his feet firmly in the worlds of both stage and screen, and who indeed saw no meaningful distinction between them. It's something that even we who valorized the anomalous practice of that ancient lively art in La La Land occasionally lost sight of, even waxed bitter about—I'm certainly not the only L.A. theater lover who occasionally imagined what the quality of the city's stage offerings might be if the 800-pound gorilla of the movie biz wasn't there to suck up all the cultural and aspirational oxygen. Of course, that's a silly daydream—without the magnet of film/TV, L.A. wouldn't be L.A., and the vast talent pool that happens to create much of the great theater there would largely evaporate, or find other lines of work.
Anyone who tries to square that circle—to imagine those two worlds together, to get them speaking to each other, even collaborating—is in for a lot of frustration and heartbreak (as I never tire of saying, there's a good reason I decamped for New York). But Cates' exemplary career clearly shows he was a tireless optimist, a true believer, as well as practical problem-solver. L.A. has no shortage of true believers in its dream factory, and despite the odds it has an encouraging number of adherents to the impractical, underrecognized cause of L.A. theater, but (with the possible exception of Joe Stern) no one embraced and celebrated both of them as fully and effectively Gil Cates did. He will be missed, indeed, but that's what I'll miss him for most.
For a more personal, and surprisingly moving, tribute, you couldn't do better than Charles McNulty's in the Los Angeles Times.