Looking at adding articles to my website which is a Paid Surveys site. I am unsure of what kind of articles i should have. For instance, would it hurt my rankings for survey related content if i had articles that didnt mention surveys but talked about another work at home oppurtunity.

No! It won't

That won't hurt. But then again try to stay focus on your theme / topic. Make it easier for the SE to decide what your site is all about.

SEs rank PAGES not sites, every single page could be on a different topic and it wouldn't matter in the slightest!

The same people who go on about "themes" for websites are usually the same ones prattling on about "article directories being great" and there, just about every page is a different topic!!