I think I recall seeing the DAM listed for the Multi-plas on one of the gameplay videos. It was listed like (number) rather than (number) x (number of shot). I understood that all shot throwing weapons would have their damage listed as the second example. So if this is accurate, and not a mistake, then the Multi-Plas is more probably a full auto plasma rifle rather than a plasma shotgun.
As I said, I won't trust any of the trailers.
The first gameplay trailer had a former big gun having the STR requirement of 4 or 5 which Josh noticed by us here on the forum and edited it.
So, I won't consider it confirmed in any way until the game has been released or if Josh decides to confirm it himself here on the forum.
Honestly, I don't know if I even want a plasma shotgun, I mean a laser shotgun worked but plasma? Wouldn't it have to be as big as the gatling laser or something.