The main element in their business model remains the gap between...

The main element in their business model remains the gap between what they pay to office owners and the rents SRV charge to its customers (=co workers) :
- lease revenues of 224 m$ for SRV,
- vs lease expenses and other occupancy expenses of 147 m$.

Another way to say it : when SRV pays 100 $ to an office owner, it is able to charge 152 $ to its customers.
And this calculation is based on an office occupancy rate of around 70 %.
So the potential at 100 % occupancy rate would be much higher and would correspond to a revenue of twice what they are charged by their owners.

Of course, this is a very basic calculation which ignore the service business and the other costs for SRV (in particular marketing expenses and administrative expenses).