Answer:
Yes, it does. Remember that you can only see an object because of the light from it that travels towards you. You can see up a tunnel when you are standing at the bottom of it, which means that light can reach you.
Of course, you may not be able to see the light from an object if something is blocking it. You won't be able to see the entire tunnel because the slope will mean that part of the light from the upper part of the tunnel will be blocked by the roof.