If one just states "has been employed" without mention of duration, it means the employee has worked for the company in the past, but not currently. However, one can say "has been employed for 2 years", for example, to indicate both current employment status and duration worked so far. ... She is still employed.

What means currently employed?

An individual has current employment status if – (1) The individual is actively working as an employee, is the employer (including a self-employed person), or is associated with the employer in a business relationship; or. ( 2) The individual is not actively working and –

Which is correct employed with or employed at?

Re: Employed With/By

Both are correct. "With" is more informal, and gives the idea of collaboration between employees and companies.