Income from casino

Assessee has income from Casino, he had not paid any tax till date, on the other hand he had many debts made for the purpose of investing in casino , now he wants to pay the tax for this assessment year. Creditors were forcing for repayment, can he claim the interest amount on the loan as an expense, if so whether he should pay only in CHEQUE or can he pay in CASH? Do any problems will arise if he pays in CHEQUE as he had not paid any tax till date? And what were the requirements to claim interest as an expense...