Does it influence something to be a member, elder or colider within the alliance?
Different privileges assigned within the alliance for different alliance functions.
Being Leader, Co-Leader, Elders do not grant any advantages or disadvantages for game play.
then it does not influence the possible rewards for titsnes, chests or any event?
Nope. No difference in game play.
Monster Chests are filled by yourself at your own speed, the loot is random.
Hero (Raid) chests are again filled by yourself, what you can potentially get could be influenced by your loot arena tier that you are in (e.g. Bronze, Silver, Gold, Platinum, Diamond), doesn’t mean you won’t get bad loots from the Hero chest even in higher tiers though.
Titan Chests are filled by your efforts along with your alliance members. So 5 killed Titans fills that chest, and loot is random.
In Titan Loots, your Titan damage performance is compared against other members of your alliance, which determines your loot tier (whether the Titan is killed or escaped). Below is a good read.
Quest Rewards that are announced are the same for everyone, the unannounced loots are randomized, as if you were doing a map level. Exception is the Uncommon Recruits 2 Quest, where there is a potential for a Troop Token for finishing the last level, it is unannounced on the quest map as a reward and may not always be there. But if it shows up for one person, it will show up for every player who plays that instance of the quest.
Challenge Events do test your gameplay against other players, but the other players cannot influence you other than placing higher or lower than you are on the point total, which determines the final rewards you get.
War Chests are filled by your contribution to Alliance Wars, the more you participate, the potential for better loots are available to you each time that box is filled at 25 points.