Many Wilton cake pans take one box of cake mix, but it depends on what size Wilton cake pan is being used. Wilton cake pans bigger than a 9×13 inch pan will use more boxes of cake mix.
Wilton provides a detailed list of how many cups of cake batter are needed for each different pan size and shape on their website. For most pans, fill them one-half to two-thirds full of cake batter. If using a shaped pan, it is important to put as many cups of cake batter as the instructions for the pan say to use.