anything is possible, so yes. bitcoin is a digital currency. We can earn it online, we can spend it online, even we can convert it to fiat money online. I am earning a living with bitcoin and I am from a country where bitcoin is still a mystery.
How do you earn a living? is it really sufficient?
No. How can it be? The price is not set, so the amount you make at any given time is not the same. So you can not rely on that.
One week you can be making $100 the next $80. Your bills not change, so you can not set a limit of how much you can make.
I guess it's far easier for people living in asian countries to make a good living with bitcoin. Since they can pay their rent with 1 bitcoin.
For the EU or US you can hardy buy all your groceries with bitcoin. If i would have the chance i would do it btw.