I own a small business with one employee. They re declaring 2 dependents what will my monthly deposits be to the IRS?

Without knowing what your net income would be, I have no way of calculating what the deposit amounts will be.

You need to make monthly deposits of the federal taxes (income, Social Security, Medicare) withheld from the employee's paycheck. Those amounts are driven by the withholding tables in Circular E.

You also need to deposit the state tax withholdings.

For yourself, you have quarterly estimated tax payments to make.