Main page title - sub page titles question

[Catfish]

Lets say my main page is targeting the keywords "poker tournament". Is the fact that my site ranks high for those KWs going to lead to subpages with keywords like "biggest online poker tournament" ranking higher as well, even if those pages are not SEO'd as well?
Or does Google look at the subpages' SEO in a way where the subpages' ranking is independent from the main page?
What I trying to find out is about my chances if I add poker articles to a website that is otherwise unrelated to the topic of poker, and still rank high with those articles for poker related kws?