Variance is the same thing as standard deviation (they describe the same thing at least, variance is sd^2). Winrate doesn't affect variance.
However, as your winrate decreases, you can expect larger swings. This is affected by your coefficient of variation, which is the ratio of your standard deviation to your winrate, SD/WR.
Here's a good thread about swings and their relation to winrate:
http://forumserver.twoplustwo.com/showfl...e=0#Post4129565