How much sugar in a tablespoon of simple syrup?
Did you boil off/evaporate half a cup? Assuming this to be true, you should now have 1 cup of sugar vs 1/2 cup water, or 2 to 1. So yes, 2/3 T of sugar.
But why would you boil it? Don't think the sugar would lose half of it's volume in the phase change to liquid, so that doesn't seem like the case...