Is income from 401k gains or dividends considered income as pertaining to child support

In most states any form of income is included in the calculation.

I agree with cdad- generally child support guidelines include any source of funds available to the parent .

http://family.findlaw.com/child-support/child-support-determining-parents-income.html

Just to be clear - you ask about "401k gains or dividends," but I think that you meant "401k distributions," correct? If you are not taking distributions from your 401k then you have no income from it, even though the value of the account may be increasing due to gains, dividends, interest etc from the underlying investments in the account. The account itself is considered an asset, and the portion acquired during the marriage is considered a marital asset that normally gets split 50:50 between the two ex-spouses when they divorce.