I heard about Robert H. Schuller yesterday on NPR because the Crystal Cathedral is bankrupt.  I wondered if perhaps some of the Word of Faith churches derived some of their theology from from Schuller's positive thinking.  Some of the Word of Faith concepts certainly sound like positive thinking
Even the wikipedia article on Word of Faith references this:

'Within the Word of Faith teaching, a central element of receiving from God involves "confession". This doctrine is often referred to as "positive confession" or "faith confession" by practitioners, and "name it and claim it" or "blab it and grab it" by detractors. The teaching should not be confused with Norman Vincent Peale's concept of positive thinking.'
'Likewise, according to Word of Faith teaching, "negative confession" can yield negative results, and hence believers should be conscious of their words.'

A big difference, at least on the surface, seems to be that the Word of Faith focuses much more on the text of the Bible and Jesus.  Of course critics would probably point out that they seem to pick and chose which scriptures they choose to focus on, but that's a discussion for another time.

I think it's a bit of a dead end, though, if you're looking for a connection between Word of Faith and positive thinking.  It really seems they've emerged independently.  If there is a link, it may only be that Robert H. Schuller's popularity rose during the period of time that the Word of Faith movement gained popularity.