As others have said, they'll wear gifted outfits- but not all the time. Each villager basically has a "wardrobe" they'll pull from. But, the more cute clothing you give her, the more she'll have to choose from, and the less likely she is to wear her original clothing! Unfortunately, she doesn't have the fashion hobby, which would mean she'd change clothing much more often.
To be clear, as far as I can tell, they won't change things like their workout gear or raingear. They'll change their basic outfit but I have yet to see villagers stop using their default "specialty" outfits.