"決定の依存" means that someone is always relying on others for some decision making. Such a person will not say what he or she wants to do. For example, he or she is asked what he or she wants to eat for dinner, he or she may say "Whatever" or "You decide" etc.

I don't think that "他者追従" is equal to "peer pressure". "peer pressure" is "peer pressure"--pressure from peers, like classmates. "他者追従" will be to follow someone else's opinion or activity.