How to check if the IR remote control works (GPIO)?

Did you also choose the lircd.conf for your remote in OSMC settings app? Or supply your own?

You can enable debugging and tail your log file from ssh, that will show your keypresses if it’s working properly. here’s a link to show how to tail the log.

You can also easily check that your remote is sending a signal by aiming it at a (cell phone) camera to see the flashes.