In short, it depends entirely on what you post and how often.
Search engine optimisation is a complex topic and there is no one single ‘magic’ thing will help your website rank better. It takes hard work and sustained effort. That’s the bad news out of the way – now for something more promising!
Where having a blog will help hugely towards your SEO campaign is if it has non self-promotional, keyword optimised content published regularly – ideally every other day but at least twice per week. Working this way starts a snowball effect that I’ve seen happen on my own site; each article published adds a new page to your website so Google sees that your site is kept current and is in continual growth, therefore relevant – your overall rankings increase a little.
With increased rankings you can expect to see more visitors arriving at your site – if the content is relevant to their search and they don’t click straight back to Google, Google sees your site as relevant to the search term and improves your ranking a little. With higher rankings comes more traffic and the cycle starts again but accelerates a little. You can see how blogging good content regularly can start to improve your search rankings but you have to keep the momentum going.
This is all well and good but one of the main ranking factors is inbound links to your site from other websites. A blog can help you here too – ideally your articles are so useful or remarkable that people reference them on their own blogs and bookmark them on social media sites – now you’ve struck gold! An added benefit of this is you get more traffic from these links – your rankings go up a little…