can you promote youtube channel in giveaways?

May I suggest you read the FAQ ("Help") and guidelines.

Advertising
Advertising is when you are promoting products or services you are associated with, or when you are posting content that is paid or sponsored. Directly naming or linking to an associated product or service will always be viewed as advertising. General references (e.g. referring to your "website", "YouTube channel", or "Steam group") may also be viewed as advertising when we believe their purpose is to bring attention to an associated product or service for publicity or sales. Below is a breakdown of when advertising is allowed in our community. Remember, the above rules regarding user content still apply. For example, we might allow you to advertise in giveaway descriptions, but that does not permit you to post referral links or link to your website with illegal content.

Giveaways
When creating a giveaway you are able to write a description. In this space you are welcome to advertise your products or services, including social media channels (e.g. Facebook, YouTube, Instagram, and Twitter), games, groups, curators, or other giveaways.