Current codes regarding fixed seating (typically IBC) offer formulas based on occupant load and a number of other variables that include:
Location/number of exits
Location of handrails
It is the responsibility of the architect to convey the code jurisdiction for a project to the seating supplier to ensure the layout is drawn correctly
Current code (IBC) designates passage at 12" for seven chairs with access to one aisle, or 14 chairs with access to two aisles. If a row has more than 7 / 14 chairs, formulas are used to calculate the minimum clear passage.
For a section of chairs with access to one aisle, the formula is "No. of Chairs Over 7 x .6" + 12 = min. Clear Passage".
For a section of chairs with access to two aisles, the formula is "No. of Chairs Over 14 x .3" + 12 = min. Clear Passage".