You could simply do this:
post.post_reviews.count
post.post_review_votes.count
If you have all the associations defined as you say.
or if you want a method for it...
In your Post model:
def post_votes_total
self.post_review_votes.count
end
As long as you have defined the relationship in Post:
has_many :post_review_votes, through: :post_reviews
Since you are passing the @posts variable to the view :
post.post_votes_total
Using the built in association methods in the views is fine, but if logic gets more complicated you should really use a model method or a helper method.