Yes, STAFFERS is a Scrabble word!

Letter values in Scrabble US: S 1, T 1, A 1, F 4, F 4, E 1, R 1, S 1.

Is it a valid word?

STAFFERS is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

an employee who is a member of a staff of workers (especially a member of the staff that works for the President of the United States)

Also: staff member.