How long has she had it? good question. Possibly since she came from Romania 5 years ago. It wasn't a standard test then and I didn't know enough to ask for it.
Can she survive it? I don't know, she has been losing weight hand over fist. With help from the vet, she can have some quality of life for as long as she has, and I am trying her on fortiflora which has helped a friend's cat with FIV.
The scary thing is that it is possible that she has passed it to the others. However, FIV is harder to catch than FelV, and Rosie has never been a fighter so we can hope they all escape it. Also, a healthy cat with FIV does not necessarily develop all the symptoms, even as someone with HIV isn't necessarily about to drop dead, it's a question of maintaining their shots, keeping them on probiotics and good food. We have recently gone grain free which I am hoping will be generally a good thing.