The satellites don’t know or care where anything on Earth is. They know where they are, and send a signal by which your receiver can calculate where it is. If you are standing in the “same place” somewhere in Japan that you measured last week, your receiver will now read 8 feet to the left, in terms of latitude and longitude. The “same place” has moved, so the coordinates are different. The coordinates read different than a map, now, not because GPS is off by 8 feet, but because your map is now off by 8 feet.
It’s the Japanese maps that now need correction, because of the earthquake, not GPS.