How much money can I earn by filling out surveys?

Well, you will not earn enough to get rich! Payment varies for each survey and generally depends on the length of the respective survey. However, this could lead to a nice discretionary earning if one registers with several market research institutes.  As a rule, you are paid about $5 per survey - depending on its length - but you can even earn up to $15 for surveys on special topics or with special requirements. This can lead to an appropriate hourly income if one is invited regularly to participate in surveys.