If you need to determine sample size for your survey when a variable of interest is a binary outcome, you can use power analysis and decide how many subjects you need to reach out for survey participation. You should also adjust the sample size by expected response missing rate. I wrote an Excel file for sample size calculation:

https://drive.google.com/file/d/0B7AoA5fyqX_sMkZJOUZxN3JvbUk/view?usp=sharing

Reference:

http://www.surveysystem.com/sscalc.htm

Thanks: Mr. George Ohashi for showing me the function that adjusts sample sizes by expected missing rate.