Well let's take a look at this, I wonder myself.
*does a little research on Wikipedia*
A set of behaviors, and the senses of self and belonging which these behaviors represent, are collectively used to define a given lifestyle. The term is defined more broadly when used in politics, marketing, and publishing.
A lifestyle is a characteristic bundle of behaviors that makes sense to both others and oneself in a given time and place, including social relations, consumption, entertainment, and dress. The behaviors and practices within lifestyles are a mixture of habits, conventional ways of doing things, and reasoned actions.
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Well if gaming actually affects your behavior, such as your social interactions or dress, seems to me it can be a Lifestyle. For many people it is. I wear gmaing T-Shirts. I go to game clubs and gaming expos, and I made most of my friends through gaming. I'd very much call it a lifestyle.
Though I'd really classify it as part of the "nerd/fanboy" lifestyle, but it's certainly there.
Also, as part of that
". Some commentators argue that, in modernity, the cornerstone of lifestyle construction is consumption behavior, which offers the possibility to create and further individualize the self with different products or services that signal different ways of life."
IF this is the case, if what you consume is gaming related, that in will of course have an impact on your lifestyle.