As long as you want to create many small images (like 512x512) you can spread it over multiple GPU. A friend is running cloud instances with up to 8x GPU and 8

As long as you want to create many small images (like 512x512) you can spread it over multiple GPU. A friend is running cloud instances with up to 8x GPU and 8x stable infusion + api in parallel. He uses simple a simple round robin with a reverse proxy in front to spread the work. AFAIK there is no feasible method to spread work on the same image over multiple GPU yet.