If I have a rental house that’s giving us $377 positive cash after mortgage is paid, how much in taxes will be owed?

If you have a rental property that gives you a $377 positive cash flow after make the mortgage payments and if there are no other expenses that you incur with regard to the maintenance of that property which you hold for rent then your taxable on the entire net amount so if after paying the mortgage payments it will depend on whether the taxes and insurance are held in escrow in our party your payment or whether you pay those separately. If there are other upkeep expenses of the property of course you're entitled to deduct those in arriving at the net amount of taxable income.

You need to talk with your accountant. Are there other costs associated with the property, e.g. liability insurance, taxes. It also depends on your tax rate.

The rental income is taxable, but you can deduct other costs such as cost to maintain, un-reimbursed expenses, property taxes, etc.

It depends on your Depreciation calculation. You could have positive cash flow but a negative tax income.