That's frankly a gotcha question from Grassley.
It depends, first of all, on whether people donated to the Red Cross in general or to Harvey Relief in particular. Just because you donate to the Red Cross today doesn't mean it's going to help Harvey people, you have to click the link specifically for Harvey donations.
Money designated for Harvey relief has to be spent on Harvey-related expenses, i'm pretty sure that's the law, or if it isn't, it's a deeply-held standard for every charity. You don't spend restricted money on something other than what it was designated for.
Which also doesn't mean that the money is going directly to physical outputs. It pays for wages and salaries for workers in the company who are spending time working on Harvey relief.
Large charities are going to do better on their "percent for programs" ratio because of economies of scale. Homeless shelters, for instance, typically do poorly on those ratios because an individual shelter can only handle a few dozen to a hundred people, but have to pay a lot of overhead on the facilities because it doesn't actually cost that much to directly shelter people.