Would we be able to see the different color variations within a nebula as seen from long term photo exposure..

Question

if we were closer to the gaseous clouds?

Answer 1

To a point. Distance doesn't matter too much although the farther away you are, the dimmer the light will be, and the more "dust" the light has to pass through will sometimes make the light redder (just like the way the sun or moon looks reddish when they rise or set).
The real deciding factor is that photos can collect light over a period of time and the effect is accumulative. Your eye only shows you the color you see at one instant.
Try this analogy: If you look up into the sky when it is raining, you see the raindrops falling and get a "snapshot" that it is raining, but you really can't tell how much rain is falling in the storm. To do that you have to look at the ground to see the puddles. Only then can you tell how much rain has fallen. The puddles are like the long exposure photos.