Tracy, slow down and take a breath. What clinic are you going to? What tests or exams or questions prompted this claim of "advanced stage"? ALS isn't cancer and thinking about "stages" often is like trying to read a book in random chapter order. Some clinics are better prognosticians than others and many PALS defy predictions.
Second, the choice to do hospice and when is totally down to you two, not any clinic or any doctor. And no one should be forcing choices on you as if you were on a used car lot. You can ask for a hospice order any time. What they should have said is just that.
The best guide of how much nutrition he needs via the tube vs. by mouth is his weight and nutritional status. (And many of us recommend real food, blenderized, over commercial formulas.) It doesn't matter whatsoever what "they want." It's what you and he want, and what he needs.
The best guides for "how long" are breathing (doing well on BiPAP or pre-BiPAP as opposed to feeling air hunger, choking, aspirating, coughing uncontrollably, etc.) and nutrition. If you have more insight to share on those, we can be more helpful. One thing I know many of us would say is that clinics are not the last word, they vary quite a bit in terms of helpfulness, and many of us stopped going well before death. If you don't feel helped there, you have the right to seek ongoing care from any doc or nurse practitioner you like.
The reported median (half more, half less) survival in ALS is 2 1/2 years, but 20% of PALS live 5+ years, 10% 10+. Those are old numbers, but hopefully they persuade you that two years in is hardly an automatic death sentence.
ALS is an incurable disease. A trache is a serious lifelong commitment, the disease continues to progress (in terms of mobility losses) and most people here did not choose it. But read some of the threads here if you are possibly interested, and you will see many of the major pros and cons.
Tracy, we make worse decisions when we feel under pressure, so above all try not to be that. Do something fun with him tomorrow and ease into the conversations that you want to have, do your research, ask whatever questions here you want, nothing's too big or small.
Best,
Laurie