Speculative fiction magazines are doing relatively well because the standing of speculative fiction in literary circles has risen so much.
50 years ago, it was largely considered pulp and not real literature (though I would argue that plenty of "real literature" was being written in the genre, it just wasn't widely accepted as such by contemporaries). Even the few works that were accepted, people often claimed that it wasn't really SF.
More recently, it is increasingly being accepted that being SF doesn't inherently reduce something's literary value, so SF magazines have had more room to grow.
Even with that, a lot of the traditional leaders among SF magazines have been struggling. What's doing well are the newer online-first magazines, most notably Tor.com, which has boatloads of money to throw around (by short fiction standards) and doesn't need to be financially self-sustaining because it is effectively a loss-leader for their novels.
Mid-tier genre mags still pay. The pay may suck, but they do pay. Even some fairly low-tier ones pay.
Mid-tier literary journals generally don't, and their editors often act insulted if the topic is raised, so the issue doesn't seem to just be that they can't afford to pay. There's seemingly an expectation that until you've already "made it" you should be working for free.
50 years ago, it was largely considered pulp and not real literature (though I would argue that plenty of "real literature" was being written in the genre, it just wasn't widely accepted as such by contemporaries). Even the few works that were accepted, people often claimed that it wasn't really SF.
More recently, it is increasingly being accepted that being SF doesn't inherently reduce something's literary value, so SF magazines have had more room to grow.
Even with that, a lot of the traditional leaders among SF magazines have been struggling. What's doing well are the newer online-first magazines, most notably Tor.com, which has boatloads of money to throw around (by short fiction standards) and doesn't need to be financially self-sustaining because it is effectively a loss-leader for their novels.