Actually, there have been quite a few historians who have noticed a link between them. R. Scott Clark draws some connections in Recovering the Reformed Confession. I think D.G. Hart draws some connections in his Seeking a Better Country: 300 Years of American Presbyterianism. There are more, and in fact, my church history professor mentioned some connections.
I know that Whitefield was originally associated with the Wesleys in their Holy Club. Also, one of his first sermons was "All Men's Place," in which he said that every man should remember the place (and time) of his conversion, and that if he didn't, he needed to be converted.
There are some similarities. There are also huge differences. I think the people making connections are wise enough to avoid equating the two figures. Whitefield, though flawed, was greatly used of God. Finney was a scourge upon the soil.