Firstly it was just a bit of fun but from memory...
Twitter was listed as having 2 data centers and a couple dozen satellite offices.
I forgot the data center estimate, but most of those satelites were tiny. Google gave me the floor area for a couple and they were for 20-60 people (assuming a desk consumes 6m2 and dividing the office area by that).
Assuming an IT department of 20 for such an office is rediculous but I was trying to overestimate.