Has anyone ever died by an airsoft?

There has only been 1 recorded death during an airsoft game and it wasn't even Airsoft related. An elderly man had a heart attack while playing.

If you mean simulated deaths, then yes. If you are hit by a BB you are out and you must yell "HIT!" and raise your hand or put on a "dead rag".

People have died from BB guns however. BB guns fire metal projectiles at high velocities. Airsoft guns are far more fun and safe.