I guess the big question is, which gift shops are you asking about? I know you can get them at the Meadows Trading Post and the Settlement Trading post at Fort Wilderness. I have been in other Gift shops (Contemporary and Polynesian) that seemed to have a small selection of household/kitchen items. While I didn't look specifically for Liquid hand soap, I am sure some will have it.
Do you need "Liquid Hand Soap" specifically? What about Hand Sanitizer. I am positive that you will be able to get that at MANY locations.