Would #1 sound right as it is? Or should I change "have" into "had"?
Either one can be OK, depending on the context.
For example, if the survey was conducted a long time ago, and most of the people who were surveyed are no longer living, then using past tense would be more natural.
If the survey was conducted quite recently, present tense is more natural, because presumably the people who were surveyed still hold these opinions. But past tense is OK, too.
Also, it depends on what the author of the sentence wants to stress (emphasize). If the author wants to stress that these opinions are still applicable (i.e., the people who were surveyed still feel this way today), then using present tense is better.
In short, I would recommend the following:
- if you want to stress the results of a survey
at the time it was conducted, use past tense
- if you want to use the results of the survey to show how people still feel today, use present tense.