After a couple more donations, I have found the formula to be a bit off. I recieved more luck than the formula granted I could. Here is my current donations, rank and luck gained, will continue adding to formula, but first must do some gold farming, Here are my current results.
DONATION | RANK | LUCK GAINED
800g EARL 1,2,2,2,2
1400g EARL 5,4,2,3,5
2000g EARL 7,4,7,6,3
2500g EARL 9,6,8,8,6
3000g EARL 8,8,10
3500g EARL 7
4000g EARL 8
4500g EARL 10
5000g EARL 11
I will be doing more testing with these gold amounts, so as to see the variable high and low ends of each, just to get a better idea of what the average would be. Will repost when I have more data. Each # under luck gained section, is a separate donation. Going to go for 5 of each increment to start off with.
EDIT: Added more data.