Most of the manufacturers of toning shoes claim that they do!
Plantar fasciitis is a painful condition where there is pain under the heel and it is usually more painful in the first few steps after getting up from rest (more so after sleep in the morning). The better treatments for plantar fasciitis seem to be foot orthotics and lots of stretching. There are also a number of physical therapy methods that are useful. While many look for a secret sauce, there is no magical cure. From what I understand it all about reducing the force in the plantar fascia. The is some good advice how to do that at this website.
What about toning shoes? There are anecdotal reports that they can help and as mentioned, the manufacturers claims they can help. There has only been one piece of published research on this and they found that a combination of foot orthotics with a toning shoe gave the best result, but this was only a short term study.
My advice is to give other methods a go first, then try the toning shoes later.