Every job has a salary range. It is almost impossible for a counter offer from a future employer to jump 40%. Your current employer may do this to keep you because you already proved your value. I doubt this plus he doesn't have another offer that is 120K.
It is also suspicious that which company would fire a new hire within one week unless there are some background related issues (criminal records, fraud, resume dishonesty, etc.). If it is due to job skill incompetence, it is usually happened during 30 days or 90 days introductory period but one week is too soon.
