A website having a pagename as websitename.com/abc belongs to a specific page which needs a boost in ranking. The same site has a blog in which if a blogpost of high content of 500+ or huge blogpost if made with a link at the end to websitename.com/abc has been posted. Now this post will benefit websitename.com/abc in ranking or the blogpost such as websitename.com/blogpost will get the boost in rankings???
If I understand what you're saying, that someone writes a blog on site.com/blog and links to site.com/abc, then yes there could be some residual "boost" in SEO power for the entire domain. Google will crawl the new post and see the internal links and crawl them as well. There is a chance that your 'abc' page will also just gain more traffic due to a link from a well written post. This is why internal links on a website are essential to getting more organic search traffic.