Nate Silver looks at the gender gap in 2016 presidential polls. Cue up all the suggestions to disenfranchise one gender or the other.
Here's a quick way to estimate it. In the polls I cited above, Clinton is doing 10 points better among women than among the electorate overall. So we'll add 10 points to her current polls-only margin in every state to forecast her performance if women were the only ones who could vote. In addition to the states where Clinton is already leading Trump, that would put her ahead in Alaska, Arizona, Georgia, Kansas, Indiana, Missouri, Montana, South Carolina, South Dakota, Texas and the 2nd congressional districts in Maine and Nebraska. Clinton would win 458 electoral votes to just 80 for Trump.
If men were the only voters, conversely, we'd have to subtract 10 points from Clinton's current margin in every state -- which would yield an awfully red map. Trump would win everything that could plausibly be called a swing state, with Clinton hanging on only to the West Coast, parts of the Northeast, Illinois and New Mexico. That would yield 350 electoral votes for Trump to 188 for Clinton.