You're comparing a 900lbs Gorilla to a 300lbs Gorilla and sort of overlooking that they're both Gorillas.
I think the argument is that the 300lb gorilla is actually an overweight chimp.
If you count on-site, full time contractors at Google you get closer to 250,000.
Give it time. My guess is Google will be well over 300,000 by 2030.
IBM has 352,600 which is about 3x the number of employees that Google has.