df <- data.frame(`var 1` = c('a','b'),
                 `var 2` = c('a','b'),
                 `var 3` = c('a','b'),
                 `var 4` = c('a','b')

)

question <- 'var 3'

dfDynamic <- df %>% count_(vars = c('var 1', question))

Error in parse(text = x) : <text>:1:5: unexpected numeric constant
1: var 1