It is undeniable that vote to evict helped Sam and also the twins. To vote to evict, you generally have to really dislike someone to bother to do it, especially when there were bigger fish to fry each week and so the bigger characters go. This is what happened with Dan - he was another marmite character like Dexter and so, although he had a lot of fans, all of those who disliked him, got their chance to get him out. In a two way vote, it would have been a different result, but as there were 3 up, obviously the most controversial of the 3 was evicted. In a vote to save, it is highly likely that Sam would not have had enough fans to keep him in, particularly during earlier weeks when he hadn't featured much.
What I'm also surprised at is the number of Sam fans on this forum who have suddenly come out of the woodwork. Up until a few days ago, he was nowhere near as popular on here as Gina and Dexter, but now he suddenly seems to have an equal number of fans. I'm wondering how many of them merely voted for him as an anti Dexter / Gina vote, because they didn't like them, rather than being real Sam fans? I do think this probably helped him to win against the marmite characters.