Recently, I finded and restored a T12 40W fixture and I want to use it. I cant find a T12 40W tube, but I can buy a T8 36W tube. It will work?   

Assuming you are talking about switch start (preheat) on ~230V mains with appropriate starter, yes you can. The 36W lamps were introduced as a drop in replacement to work with existing 40W T12 gear and starters, no modification necessary. Same goes for 20W T12 lamps that are replaced with 18W T8 lamps.

If you're working with ~120V mains and rapid start ballast, then no it won't work as the ballast open circuit voltage is not sufficient to strike an arc in the lamp, especially with the krypton buffer.

The fixture is a preheat, with a 4-5
65W starter in a 220V local current, it will work?

It should. Try it. The worst that could happen is it won't light. I'm sure it will, however.

There is no problem to start 36W T8 on an 40W T12 220V choke + starter.