Bad idea to foster Russian blue?

My friend needs someone to watch her cat for a year. Is it a bad idea to keep her Russian blue cat that is 7 at my apartment? I read they don't love strangers and will poop or pee elsewhere if the litter box is dirty. Any insight on whether I should pull out or will we warm up to each other???

If the cat is going to live with you for a year, then you won't be strangers for long.
   
At first the cat may be aloof but over time will become accustomed to you, particularly once the cat figures out that you are the source of its food.
   
You may even find that when you friend comes home, the cat will prefer you at first because you are the one it has been living with.
   
If you are concerned that the cat will spend the year wetting and pooping everywhere but the box, well if you keep the box clean, then the cat is unlikely to soil elsewhere.
   
If you do not keep the box clean, the cat will find this unacceptable and will relieve itself elsewhere.
   
If the cat soils outside the box, be sure to clean the area it wets or poops with Nature's Miracle or the like to completely irradicate the smell.
   
If you do not, the cat will continue to smell it's past soilings and they are like beacons screaming, "PEE HERE, POOP HERE" that the cat will be unable to resist. This is why animals return to the same spots over and over to relieve themselves; they are urged by scent to do so.
   
So that is, to a large extent, up to you. If you scoop and change litter frequently you should have no trouble, as cats tend to be fastidious creatures and prefer to soil in their boxes.