betta won't eat

I have a betta, not sure of his age but probably about 2 years old. No
change in tank, water, etc. he is in a 1 gallon lighted tank with underwater
filter. This past month he has been laying around 95% of the time, on the
bottom of the tank. He was eating a little bit, albeit not much, up until 5
days ago. He has not eaten in 5 days. He will swim if I pretty much make
him move. Is he just old and about to die? I mean, I know he will die if
he doesn't eat soon, but it doesn't appear that he is going to eat.