There is no way of knowing this, except by a firsthand experience as people start using it once it arrives. Corning did unveil the fifth iteration of its famous Gorilla Glass quite recently. Since Apple is known to use Corning's glass, chances are that the iPhones 7 and 7 Plus do indeed have the new Gorilla Glass 5. But again, historically neither Apple nor Corning ever confirms which version of their Glass a particular iPhone model has. So there is no way of knowing that either.
It is worth noting here that this time around, the new Gorilla Glass focuses on drop protection and toughness. Hence, it won't be surprising if its scratch resistance does not better Gorilla Glass 4.