We think my friends cat wont make it through the night, or is the way she is normal. HELP?

my friends cat is very sick or at least we think. her name is sadie and she's 17 years old. she is just sitting there not moving at all only her head and she hasn't been eating. when you pet her you can feel each rib, she's scary skinny. her eyes look like they have sunk a little into her head. and she's breathing very fast. do you think she will make it through the night??? please help. :(