It varies widely.
As a rough rule, if you raise every dilutive round you can, the VCs will end up owning 80%. The employees as a group will end up owning 10%. And the founders together, the other 10%.
A good example is Box, where Aaron Levie was diluted to 4%, but they re-upped to 6% via additional grant(s) from the board:
This is what happens when you do 5+ rounds of VC financing, including the first 2 at very dilutive prices.
But … it’s all about the # of rounds of dilution you take, and when.
Atlassian did just one real round, a pre-nicorn round with Accel once they were at scale:
And so, pre-IPO, the Atlassian co-founders owned 75%. As a result, each today is a billionaire.
Some more case studies here: