Lots of good insights have been posted already. You can have the best content anywhere but if nobody knows about your website the content will just sit there. On the other hand, you can drive huge amounts of traffic to your site by implementing the best marketing plan in the history of the internet, but if the design, navigation and content of your website stinks then you've wasted your time and money. Both are needed, but I tend to agree that for the long-term content is what will keep you in business. Marketing is very valuable because it provides demographics and other research that will help you succeed. But, if you aren't providing value through products or services then there is no reason for people to keep returning to your site or for them to recommend your site to others.
content is king... i have a mix of sites with me writing content and others automated and they are driven by organic listings but also building up a following. some do take time but I still rank this as a great way to make money online. PPC may be instant but is high risk and far more time consuming.
Content =/= Google organic traffic. Content is content. You know, the stuff you put on your site? Marketing is the act of getting visitors to your site whether through Google or StumbleUpon.