I have to say that I am a bit of a hard as$ about food. My older daughter is a great eater, younger not so much. She will quite happily go 4 or 5 nights a week with no dinner. It is a control issue with her. If it is something she like she will gobble it down, if not, nothing in this world will make her eat it. (even the promise of ice-cream

).
If she is hungry she will eat. I will not make a second option. We eat as a family 4 nights a week and this is where she is usually difficult. It is not difficult or spicy (that is what we eat the other days on our own).
I would cut down on food after 3.30ish. If Sophie eats after that dinner is guaranteed to be a write off. As Bizzy said - maybe just offer fruit, not the crackers and stuff.
Keep dishing it up and he will start to eat it eventually. If he is hungry, he will eat