Yes. This is income. Firstly, this wasn't your question, but your brother can't claim the mortgage even if paid directly to the mortgage company. To qualify to be able to claim mortgage interest, you need to:

1. Own the home
2. Be liable to pay the mortgage, and
3. Make the payments

Then, there are two ways to handle this depending on whether he pays less than Fair Rental Value or not.

If he pays what would be a normal rent, you'll claim it as a regular rent on Schedule E:

https://ttlc.intuit.com/replies/3288530

If he rents for less than Fair Rental Value, see this:

https://ttlc.intuit.com/replies/5921388

Is the second paragraph in the "rents for less than Fair Rental Value" section correct?

Is second paragraph in preceding answer correct?

It is only partially correct in the senses that one cannot says "since you rent below fair market price, you automatically would be considered to be renting "not for profit". There are tests as to what activity constitutes a not-for-profit activity, refer to IRS Pub. 535.