In Breaking Bad episode Hermanos, we take a peek to the past of Gus Fring where his partner gets killed by Hector.
I know it is not unusual for a character (or a real human being) to be sad and hold a grudge about it.
In episode Abiquiú, where he invites Walter for dinner he says "This is a Chilean dish that I love. But I never get to make it. Kids won't eat it." and we also see some toys in his house that suggests he has kids, however we never see Gustavo with kids, a wife or a family. Hank or other cops never mention his family. It looks more like an image he tries to create that he has a family to cloud the reality.
Of course someone making good dinner, being alone or not having kids doesn't directly mean he is gay but when combined with his desire to avenge his old cook, and his reaction when he was killed, it suggests he had feelings for him.
Are there any other hints or interviews by directors, actors, producers that support this claim?