What is the ruling on money earned and experience certificates obtained from a job acquired through lying in the written exam and personal information? And is leaving the job considered piety for which the doer is rewarded?

You must repent to Allah for intentionally lying on the exam. However, the job obtained is not rendered unlawful due to this lie. Your salary is permissible as long as you are qualified for the position and it is permissible. There is no need to leave it.