I know that for gay marriage and acceptance there's been some studies that having gay characters in TV helped shape public perception. I think the study was around people watching Will and Grace and Modern Family and their acceptance of gay marriage.

It's kind of beautiful that watching imaginary characters can make such a emotional impact since we bond with this "people". That's why representation on mass media is so important especially since most people won't meet a trans person in real life since they are a small percentage of the population. Especially if they are talking about their own life.