Currently driving a first generation 1989 V6 4Runner. Put it up in storage for the year as I went over seas. Put some gas stabalizer in the gas tank and left it. Did get driven a bit while I was gone but not too much. Enough to keep the battery charged, while I was gone driver ran it out of fuel and now the gas guage does not work well. At a full tank it shows over half and after about 100kms it shows empty for the duration.

IS there a possibility that the stabalizer ruined my guage? Do I have to replace the whole tank now? Will any tank work from another 4Runner running a SR5 V6?

The fuel level sending unit in the tank has probably failed. Common on a lot of makes of vehicles. I use the trip meter to keep track of my fuel supply since mine failed.
Take a look at the factory service manuals provided on this sub-forum to get an idea of what is involved in replacing the sender.

If you pull the sending unit out of the tank you may be able to clean it and get it working again. It's basically a wire wound potentiometer, and the windings get dirty. (They also break, so it may not be repairable.)

You'll have to pull it to know what's wrong.