It's alive, but I don't know about 'doing well'. It survives among some special interest communities, but the usage is tiny compared to any of the major platforms now. You won't find your uncle on it.
More and more often these days you'll find at the bottom of a community info page a discord rather than an IRC channel. Even big pirating communities are making the switch.
It doesn't start out that way. First you have a lot of people pushing their favourite barrows. Then they set up IRC gateways. Then they bleed users to IRC. I've been to a few conferences that keep actual statistics of messages published, and it's always the same.
But it's well hidden. No one gives up pushing their barrow, so if you just listen to the conference gossip you would never know it's happening.
Bug or feature?