Are you talking about the rewards you receive from the Disney Visa card? If so, then yes, you can by ordering your reward card and then buying a Disney gift card from either the
Disney store (online or regular) or from the stores at WDW or DL. I think the online Disney store only sells in increments of $25 ($50, $100...). An advantage of buying a gift card with your Visa reward card, the reward card expires, the gift card does not.
My mom uses her rewards to buy the grandchildren Disney gift cards for birthdays, etc.