I have lots of experience with lymphoma in cats. Its one of those diagnoses that can give you a WIDE range of survival times.
Theres different types of lymphoma (small and large cell), and lymphoma in general can affect different areas of the body - meaning different survival time.
GI lymphoma, with only local metastasis to regional lymph nodes has a far better outcome than something like pancreatic or renal lymphoma. I had a lymphoma kitty (who was horrible at vet clinics, so I did pred instead of chemo) and he lived over 2 years. I have personally treated some cats with early stage lymphoma with the more mild chemo protocols (cyclophosphamide, vincrisine, pred, or just oral chlorambucil and pred), some do quite well (even cured). Unfortunatley most cats arent diagnosed in early stage. On average, most times its found at mid stage, where responsiveness to prednisone/chemo’s varies from good to guarged. I also know cats who have been diagnosed well into an advanced state of their disease and did not respond well to treatment, or the owners decided not to treat. Hopefully if it is lymphoma, your cat is in early stage still. I do honestly know several cats who had been “cured” and some who just did tremendously well with their remission time.
Hopefully the ultrasound and biopsies will give you an answer. I’ll keep my fingers crossed that everything comes back as just inflammatory disease
I know it must be hard for you to think positive considering what you went through with your dog, but sounds like whatever this is, you have caught it early enough that treatment will probably make a difference for your kitty 
Jingles for you, your kitty and hoping for an eosinophilic IBD diagnosis!!
Here is a good short article on low grade feline lymphoma - should answer some of your questions: http://www.vet.cornell.edu/labs/simpson/docs/kiselow.pdf