False. Both of things things enormously contributed to his success. There are tons of people with drive who never even got close to his achievements, and tons more with ideal situations who never created anything of value. Gates had an ideal mix of character and good fortune.
There's also the sad fact that personality derives a lot from upbringing and genetics, so you could say that the "instinct and drive" Gates had was also a facet of luck. In a way, most of what we are is roughly predetermined. Our character is a throw of the dice. We don't even know if free will exists at all. This is why I tend to laugh at libertarians who believe they owe nothing to anyone.
Face it, luck is perhaps 90% of any tremendous success. Just because Gladwell wrote about this doesn't mean it's not true. It's not a reason to diss Gates and his ilk and stay envious and bitter; it just means we should stop basing our self worth on whether we've changed the world or not, and stop adulating important figures or trying to derive lessons from their every move. Plenty of innately great people have failed and plenty of less than adequate people have succeeded immensely.