Can the asteroid belt be seen from Jupiter? Suppose that someone lives in the neighborhood of Jupiter. He may live in a space station around Jupiter, or in any ot it's moons (I believe that it doesn't matter for this question). If this person look to the Sun he can see the asteroid belt, since it is between them? If generally not, then he would be able to see larger bodies such as Ceres?
No. The asteroid Belt is on average about 2.6 AU from the Sun.

Earth is 1 AU from Sun, 1.6 AU from the asteroid belt.

Jupiter is 5.2 from Sun, 2.6 AU from the asteroid belt. I.e. much further away.

Also, it should be easier to see asteroids from inside their orbit since they reflect more sunlight towards us. From Jupiter you would see their shadowed sides. Ceres is to Jupiter what Venus is to Earth. Venus is inside of us just like Ceres is inside of Jupiter. When it is at its nearest, we can only see a thin rim of sunlight on one half of its edge. But when an outer object like Mars is at its closest to us, we see its entire hemisphere lit up by the Sun. Add to that that when Venus is at its closest to us, as when Ceres is at its closets to Jupiter, it is very near to the Sun on the sky and therefor lost in the bright Solar light.

Ceres wasn't discovered until year 1801. That's after the discovery of Uranus 20 AU away. You'd need an even better telescope to find Ceres from Jupiter than from Earth.