That doesn't sound like a lethal dose of caffeine for a normal person.
Yeah, that's actually really not that much caffeine. We'll be generous and say 180 mg for the Dew (not sure what "large" constitutes exactly, but I went with 40 fl oz), 150mg for the latte, and probably around 100mg for the energy drink: a total of about 450 mg. Most low end cases I've read about of caffeine toxicity happen at about the gram mark, but they're usually even higher than that.
Don't get me wrong, 450 mg is still a lot of caffeine; I actually took a little over 500 mg in pills in college when I stayed up all night writing a paper and I literally just needed to stay awake through the lecture that morning to turn it in. It hurt like hell and I was hallucinating the entire lecture, and my heart was certainly taking a beating, but I didn't feel like it was a close call or anything. I feel like he probably had some sort of heart condition that compounded things. Poor dude, what a sad way to go