The gash seems to be in the tread, but not in the cords. As others have said, the cords are what hold the tire together and retain the pressure, not the tread. I've ridden tires with cuts this size for thousands of miles afterward - IF there is no cord damage evidenced by casing bulges, wiggles, etc. I've used Shoe Goo / Goop to fill in such small cuts on some tires, but this is optional.