The Dreksler channel describes “Life on Gas Giants” (Sept 2018)
Organisms like bacteria could float in the atmosphere indefinitely because of the strong winds below, in a zone of reasonable temperature and pressure.
Larger, bag-like and possibly quite large organisms could evolve (something like our own coelenterates or even octopi) and might even be intelligent and self-aware. But it would be hard for them to find materials to build things (with ocean bottom organisms on Earth can do).
Wikipedia embed of comet collision with Jupiter in the 1990s, click for attribution.