How is zakat calculated on his freelance work and olive oil press, with existing profits, living expenses, and outstanding debts, in addition to an interest-based loan?

It is not permissible to borrow from an interest-based bank. You must repent and return the borrowed amount without the interest. However, you should pay the interest if the bank forces you to do so. Zakat (definition) is obligatory on the proceeds of the olive press and other freelance businesses, provided a full year (hawl) has passed and the threshold (nisab (definition)) has been reached. Any debts you owe should be deducted from the total value of these proceeds. If the remaining amount reaches the nisab, then one-quarter of one-tenth (2.5%) must be paid. Zakat is not obligatory if the nisab is not reached after the deduction. Debt reduces the zakat on internal wealth such as cash and trade goods. As for what is spent on living expenses during the year, it is not included in the zakatable amount. Debt does not reduce the zakat on apparent wealth, such as crops. Therefore, zakat on olives is not waived due to debt.