A common phrase is "Yes-man", a person who follows someone around and gives "advice" by always agreeing with their idol. It's a derogatory word; one that the follower should be ashamed of - but they may not believe that that is what they are doing - they may simply believe that everything the person says is golden.
Another colloquial word is "boot-licker", butlicker"; and that's an even more distasteful word (exactly as it sounds!)
But a proper English word would be "sycophant":
a person who praises powerful people in order to get their approval.
This is also not a nice word - but I believe that it is the English word closest to what you are after.