[Does your Google Quality Score impact your SEO ranking? If so how much impact does it have?]
Quality scores in AdWords are composed mostly of the CTR of your AdWords ads. SERP rankings are based on your relevancy score that is derived from signals of relevance.
Part of the quality score is made up of the system-wide history of your keyword, plus how relevant it is to your ad text and landing page content. After you receive a sufficient number of impressions your own keyword CTR becomes the primary factor.