As far as I know OpenRouter has <100 employees, maybe even <50.
1-2% headcount on data is below average for a tech company but not unbelievable either.
It is true you can get a lot further than before with "just" a clean semantic layer though!
The secret here is that building the semantic layer is a ton of work, predominantly done by data people.
Far less promising companies with zero profits often have thousands more employees…