Is the father's money considered illicit due to his borrowing from banks to operate his project, knowing that he did not consume usury but rather paid interest, and does this affect the acceptance of his acts of worship?

Taking usurious loans is one of the gravest forbidden acts, and your father must repent to Allah for it. However, the money he earned from his industrial project is lawful if its field is permissible. Your father's prayers, fasting, recitation [of Quran], and all his other acts of worship are accepted, Allah willing, if he fulfills their pillars and conditions of validity and performs them sincerely for Allah. Which deeds weigh heavier on the scale depends on sincerity to Allah and following the Messenger of Allah, peace and blessings be upon him.