But how this could affect the mindset of the kids when they are also seeing these ads/promotions from the social media influencers they followed? I could be wrong but this has a mental effect on them and at a very young age, they are exposed to gambling already which is supposedly not the right time.
Children don't have much discernment of what is real from what is just propaganda. They are likely to take those ads seriously, believing gambling can be a solid source of income or a life changer if they deposit enough money to play at casinos. I believe many of us had this kind of misconception when we were on such stages of our lives, besides many other imaginary ideas which didn't match reality.
However, if kids don't have money and no way to access casinos, it shouldn't be an issue, right? They will keep imagining and dreaming about gambling, but they won't be able to put their plans in practice, unless they are raised by careless parents who give them access to credit cards, banking account apps and so on... Anyway, it's pretty easy to not let this threat go ahead. Just make sure your children aren't having access to your personal banking data.
I think these influencers must know their target audience before accepting the offer or should not be included in their blogs or videos?
Influencers do know, but they don't care, as long as money is being deposited on their accounts. They earn from both sides: from casinos and from the infant public. There is a very famous case of influencer here in my country who is included on his category you are mentioning. He is the most popular youtuber from the country and the majority of his subscribers are children, as he produces content related to Minecraft, joking and games.
Suddenly, he started promoting a casino as opportunity of extra income, although several polemics involving the respective casino and other local influencers, he stopped his advertisements and claimed to have never promoted online gambling. The guy is just an hypocritical, what isn't uncommon among social influencers.