It's pretty unbelievable but listed on the Kitchen Nightmares link it shows only 8 of the 22 restaurants visited in the UK series are still open under the same owners.
The break down;
Season1: 1 Restaurant still open
Season2: 1 Restaurant still open
Season3: 0 Restaurants still open
Season4: 3 Restaurant still open
Season5: 4 Restaurant still open
As you can see most of the restaurants still open are one from the latest season... so it should only be a matter of time before more of...