Yes, whether you win or not in the Lottery totally depends on luck(and I presume by winning the "jackpot" you mean taking the 1st place), but I was talking about another Jackpot, which is called "Daily Jackpot". For winning that jackpot you should not rely on luck at all. You just need to be the highest daily wagerer, and the jackpot is yours.

There is also another Jackpot on freebitco.in(which I won 2 times already), and you can win it by rolling 8888 in the MULTIPLY BTC game. But winning it, and its size, depends not only on luck but also on your willing to hunt for the jackpot. If you won't check one of the boxes here