Most of us who post in this thread are gamblers and we understand gambling, I suggest that OP will create a poll so we can also see what the people will think about donating money when they win.
Adding a poll won't change anything since the result can be manipulated, so there is no need to do that. What people do about their money has nothing to do with us, whatever they will use their winning for sober, investment, donate, spend or anything else.
It completely depends upon the person characteristic because there is no guarantee whether he will the jackpot. Before Jackpot, many people wish to donate after winning the jackpot, but once they won, they will forget about their promises and which I have experienced this from many of my friends.
Donated or not, it won't give any effect with your gambling result.