AmE: has
BrE: has (individually)/have (collectively)
Grammar Girl :: Collective Nouns
Thanks, Svartnik.
I've gone through the link. However, if I am not wrong, 'staff' is not listed there. I may be wrong.
Below are the definitions and examples of how to use the word 'staff' (from Collins Cobuild Dictionary).
The staff of an organization are the people who work for it.
The staff were very good...
He thanked his staff.
...members of staff...
2 N-PLURAL
People who are part of a particular staff are often referred to as staff.
10 staff were allocated to the task...
If I am not wrong, for one person, it should be 'staff member'. I stand corrected.
Thanks.