Can soda cans be used as insulation?

yes,with some Duct Tape connect them in a standing position the height of the space between top and bottom plate of wall. Make these tubes and stand them in the wall tight against each other, before wall sheetrock or plywood is up(it's easier with one side up to give cans a wall to hold them up). This will create dead air space, and considered one of the best insulators.