Is what an employee earns considered unlawful if he obtained his job by lying on his resume? And does that affect the acceptance of his prayers, fasting, and other acts of worship?

Lying is forbidden and leads to wickedness. The Prophet, peace and blessings be upon him, said: "Indeed, lying leads to wickedness, and wickedness leads to the Fire. And a man keeps on lying until he is written as a great liar with Allah." A false resume involves deception and fraud, and the Messenger of Allah, peace and blessings be upon him, said: "Whoever cheats is not one of us." You must repent to Allah, tell the truth to those in charge of the institution, and seek their forgiveness. Acts of worship are valid and sufficient if performed according to religious law, and their acceptance by Allah is known to Him alone.