Yes, I did see that. I was thinking more about going away for the weekend or longer, visits back to wherever she's from - these things can get very expensive. Cheap mini break is very possible, but a comfortable one is better. I've done both and know which I prefer.
So to answer her question about whether it's enough to live on, then yes, just about. Is it enough to live well? No, unless you want to live in a city with great restaurants and bars but not be able to go in them if you also want to fly back to see your family or take a short holiday and if you don't mind night buses instead of taxis.
If she doesn't mind living like a student, it's possible, but still not comfortable.
1000 zl not much for food? For one person?
Looking at it, it's actually about 760 zl a month, say 750 for maths' sake. Meaning 187 zl a week to buy not just food but anything else that you need to spend on day to day, a little something for unforeseen expenditures, entertainment, clothing, mobile phone top-up, hairdresser, toiletries and cosmetics, ladies' products etc (assuming Niki is a lady).
As I say, possible, but barely so and only with a bit of skill. Forget the weekends away.