Can I make a living off Airbnb?

It is possible to make a profit but not likely that much of one.

You also need to check local zoning laws. Many cities have laws limiting or prohibiting airbnb types of rentals.  I think Portland has some such laws but most of the suburbs do not.  I have never lived or worked in Portland but I do know they have rental laws that are specific to Portland that are different than the rest of the state. 

As for the Oregon coast- the key to a vacation rental is the proximity to the ocean. You will not get as many bookings if you cannot see & or hear the ocean from the rental. 

You will need to write a business plan and know all the costings before you could estimate any potential earnings

If you could rent each room every night of the year for around $140 a night more than your expenses including taxes, yes. Chances of that happening are basically zero though.