Posting this anonymously because I don't want to seem like I'm plugging myself and my management would probably get angry.
I'm a standup as well, not quite as large as CK but a number of tv spots under my belt etc.
But it's absolutely right. There's barely anything.
You're average split goes a bit something like this:
Depends where you are. On average a theatre takes around 30%. A bit less in Australia (eg Melbourne Comedy Festival) which takes about 20%-25%. A bit more in European theatres (eg Edinburgh Fringe Festival) around 40%-45%.
Booking / Ticketing fee is around $3-$8 per ticket. For the average show ticket price that's about 10%.
Management takes a flat 15%-25%.
Depending on the scale of marketing, on average it's around 15% of the show budget. The industry wisdom is at least 10% of every ticket should be spent on getting people.
If there is a huge promoter behind you, they sometimes take a stake in the show, usually around 30% - 60% and includes the marketing budget. It's not that you're trying to convince people. It's more like, if they don't know you're there, they won't come.
Then all the travel / accomodation costs.
That's if you're doing theatre shows. The other side of the coin is college campuses, corporate entertainment, which pay a flat rate. The largest gig I did was opened in a 30k seat stadium and I made $4,000.... so not a lot.
Plus you're always touring, unable to maintain relationships, getting heckled (few careers involve being openly sworn at by masses, it's not healthy for self-esteem), feeling like a self-promoting whore and constantly wanting to die because you're whole career is shouting into darkness.
That doesn't even include the opportunity cost. It takes 10 years to get to the point where you can reliably book a 1000 seat theatre. That's assuming anybody comes in the first place... Until then you're making nothing.
It's not uncommon to see someone sell out a show and walk away with very little.
Whilst what CK did is amazing. I don't think it can be done by most standups. I think it would have turned out differently if he didn't have a tv show airing already, basically he's at the top of his career.
The scary part is if standup isn't as as lucrative as it's made out to be. Theatre in general is even worse...
But hey, we're all rockstars!