No survey, just my opinion based on my personal observation

80% of diners at buffet restaurants (not just Chinese) are overweight.

less than 20% of tables are usually within 16 feet of the buffet and 90% of the tables are at least 10 feet away from the buffet.

It seems reasonable that about half of the seating faces a buffet and half of the seating faces away.

Many obese people are not comfortable sitting in a booth because of their size, thus they would normally ask to be seated at a table.
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The survey doesn't state:

how many normal and how many obese diners were in the study

how many of the obese and normal weight people were familiar with that particular buffet layout, thus determining if familiarity with the buffet had an influence on whether a diner browses prior to loading their plate with food.

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I'm impressed that the study excluded Asians. I wonder how many Italians were eating at the Chinese buffet and why was the survey done at a Chinese buffet???

My own statistic:

95% of the food at a Chinese buffet is not Chinese food.