Check this link: http://www.google.com/search?q=vitiligo+cure&hl=en&prmd=ivns&ei=rD1GTYBsxLesB7OboDg&start=30&sa=N My website is: http://www.naturalvitiligotreatment.com this is result of my 1 month SEO! I used fonts of Google API for headings and I believe this is the very quick response I got for this website - I know SEO is not a very tough job but getting result in one month seems hard. My website is just 4 months OLD and I want you to check the Alexa ranking of this website! Dig in Google and Youtube - You will surely find the website which I had read before!
So now "you believe" the fonts helped. I did that search and did not see your site. I have better things to do with my time than to "dig in Google and Youtube" to look for anything that supports your claim. You either know a specific article that supports this claim or you don't. And don't kid yourself on about your SERPs on such a non-competitive search as that.
What you didn't find? Shocking! Lol.. I just work on highly competitive keywords and this is one of them! I didn't get trophy to make you believe - Don't waste your time on this forum, I know you can do more better then digging and kidding.
You still not able stand for the statement you made earlier with the example you have given. What is missing is why do you think font had played a role.
Too general a statement. You need to specify what the font is for. What type of theme if its for a website, what type of impact if its for print etc... then we can advise