1v1s like what you're asking for never happen. The only time they ever would is on flank, and that's rarely more than trading chip shots.
Even if a MGE/ammomod-type 1v1 were to happen, say if both teams wiped on mid except for a soldier and scout on opposite teams, it depends on mostly terrain. I.E, badlands mid. scout would win because they can legitimately just keep chip shotting the soldier from choke/valley until he makes the mistake of trying to bomb, in which case it's pretty easy for the scout to clean up.
If the same thing were to happen at spire for some reason, the soldier would have the advantage if he was on spire first, and the scout would if the scout was on first. It's all a matter of positioning.