I doubt lm-sensors will interact with your GPU fans. It should work for case fan, though.

You should be able to read your GPU temperature by reading from files and control fans by writing to files that are locates in /sys/class/hwmon/. There should be scripts/programs that exist to do this already, but it isn't a very complex task, so could be scripted trivially. lm-sensors should help you identify the correct files, as well.