So that is a 10Kg sack of food, 8oz = 200g which equals one cup. So would say that it is per cup that they give the amounts for but on quick calculations and just looking at text books it looks pretty good and will try to convert the feeding guide into metric for you. Ingredients are different to nutritional value, I never look at the ingredients just the panel that says protein, fat, etc, that is the bit with the nutritional value (Guaranteed Value) not the ingredients.
Below is the feeding guide converted.
Size of cat 400g - 2kg 2kg - 4kg 4kg - 6kg 6kg - 8kg
Amount of food 50g - 67g 67g - 100g 100g - 133g 133g - 200g
Hope this helps with feeding the correct amount for them