FTA, the amount of hires they have to weed out visually intensive and traumatic material was listed at 80 worldwide. The article compares it to Facebook's hires for similar weeding out and there was a couple of orders of magnitude difference. I recommend reading the article - it was sobering how bad it is and how it continues to traumatize its victims.

Given the sizes of the two companies I'd expect Facebook to have one or two orders of magnitude more employees for most roles.