My question is similar to this question: How can I get search engines to crawl my site and see a localised view of my data?
However, I know that the obvious statement of multiple languages increases the number of impressions your website will recieve due to the large target audience. But is there any evidence that it will increase the number of impressions received on a particular language?
For instance, if I have an English website and I then introduce Spanish, German, and French, is there any evidence that your rank would increase in the UK? In other words, is this a ranking factor, and if so, is it an important factor?