in my opinion it would have to be a consistent amount of money that pays the bills and at the same time also pays you a wage each and every week whilst always having a sustainable bankroll to continue to earn more and more.
Everybody have it's own price. It depends of cjuntry where they live, prices on food and housekeeping. I think that 3000$ per month will give you all possibilities to live good in Ukraine.
Typically you'd refer to a winrate (on cash tables) in bb/100 (how many bb's won per 100 hands). Winrates (for winning players) become much lower as you move up in buyin levels (5bb/100 would be an easily sustainable winrate in the micros but probably impossible at higher limits).
I'm not sure what are considered as acceptable (or 'excellent') winrates for each level online or live. I'm sure others will know for certain.