This is a comparison of civilians (143m) and active military (1.3m). It does not state that 142m are employed by the military. You can tell that's what they mean because of this quote:
"In 2017, civilian workers outnumbered military personnel nearly 110 to 1."
Ah, my bad, I read it wrong. That makes a lot more sense! So how many people do actually receive a pay check from the US military.