Originally Posted by TwoBrad Bradley
I don’t take the meaning of voice to be that complicated. Voice is simply the screenwriter’s position on a certain subject, with the subject typically being the theme.
Though I agree theme and point of view (or position as you say) are the bedrock from which voice emerges it's misleading to leave at that.
If you have a mundane theme and hold a trite point of view on the subject of the theme your voice will be a major snooze. Not to mention characters are likely to be hackneyed stereotypes and plot, predictable.