Adding new blog content daily can help with your google ranking. That is though if you post quality content and original content.
Only post a new blog post if it will be helpful to your readers or other people searching google to solve a problem.
You don't have to post daily though and even 3 times a week is enough to keep your website looking fresh in googles eyes.
Remember though that when you post a new blog post it can take a week to a month before google is able to find the blog post and add it to it's search index.
And then once they index it google can take up to 6 month before it might rank your blog post.