Actually, they were mostly brother acts, whether they were actually related or not.
Unfortunately,it was beefcake only, and the guys didn't appear alone; there were usually scantily-clad women in the act.
Not a lot of gay symbolism. In fact, the whole drama of highwire acts, with a woman tumbling and a man catching, replays a heterosexual drama.
The acrobat tradition started failing in the 1950s, facing stiff competition from tv and movies. The last world-famous acrobat was probably Jimmy Cavaretti, and he supplemented his circus fame with appearances on tv and a spread in Playgirl.