As always, the big question is how to pay for such a major new initiative. Trump has said he'd cover the cost by rooting out unemployment insurance fraud. So the first question is how much Trump's plan would cost — and the second is whether there's enough fraud to pay for it.
Hillary Clinton's plan to offer 12 weeks of leave at two-thirds of a worker's previous salary would cost $300 billion over 10 years. Even assuming Trump's is much less generous, offering six weeks instead of 12 and a smaller fraction of salary, there isn't enough unemployment fraud in the United States to come close to paying for it.
A study published in 2013 by the St. Louis Federal Reserve found that unemployment fraud in 2011 totaled $3.3 billion, about 3 percent of total unemployment benefits paid out that year.
$3.3 billion is a lot of money. But given how much the government spends on unemployment, it's not an astronomically high fraud rate: Worldwide, businesses lose about 5 percent of revenues to fraud. Even if Trump managed to drastically reduce unemployment insurance fraud, something he's never mentioned a specific plan to do, he'd save a couple of billion at the most. Guaranteeing family leave would cost multiple times that.
Clinton has also called for paid family leave. Her plan would provide 12 weeks of paid leave, with workers earning two-thirds of their salary while they're gone. The Committee for a Responsible Federal Budget estimates this program would cost $300 billion over 10 years — about $30 billion per year. To pay for it, Clinton has proposed higher taxes on the wealthy.
"Raise taxes on the wealthy" is Clinton's plan to pay for nearly all of her proposed social programs, and it's almost certainly politically infeasible. Even some progressives have suggested that raising taxes on the wealthy is the wrong approach to paying for family leave, and prefer a payroll tax instead, making the program broad-based like Social Security.
On the other hand, Clinton's pay-for plan might be a political fantasy, but at least it would, in theory, pay for her proposal.