What is the ruling on money earned from work obtained through ill-gotten gains, and what must be done with the remaining ill-gotten money?

We congratulate you on your repentance and ask Allah to accept it and grant you success. If your work is permissible, then its earnings are lawful, and obtaining your employment contract through unlawful money does not affect this, because the money is generated from the permissible work, not from purchasing the contract. This is what is called "separation of the two aspects."

As for the unlawful money that was spent, we ask Allah to forgive you. Regarding what remains of it in your possession, there there is a difference of opinion among scholars, and its details are in Fatwa no. 63991.