How long?

My mother, after about four weeks of not being able to eat and almost three weeks of being non-responsive, is suddenly hungry and quite alert.  She has left side paralysis from a tumour in her brain, and she has difficulty swallowing.  As per her own request when she was able to make such, the IV was not replaced when it last fell out.  Right now, she's "eating" thickened water and juices to try to satisfy the hungry feeling (it's maybe a teaspoon in total of each per day).  How long can she survive like this?