In general survey data is saved in SQLs AllUserData Table in the Content Database. But the data for a “people and group” field is not. This data is stored in the AllUserDataJunctions table.
You can use the following SQL statement to get the People for a survey list with title “MySurvey”. You should also filter the result by FieldID, if you have more than one people and group field:
SELECT tp_Title ,tp_RootFolder ,tp_Modified ,AllUserData.tp_Created ,[AllUserDataJunctions].[tp_SiteId] ,[AllUserDataJunctions].[tp_DeleteTransactionId] ,[AllUserDataJunctions].[tp_IsCurrentVersion] ,[AllUserDataJunctions].[tp_DocId] ,[tp_FieldId] ,[AllUserDataJunctions].[tp_Id] ,[tp_Ordinal] ,[tp_SourceListId] FROM [SP230_Inhalt_Inet].[dbo].[AllUserDataJunctions] Join [SP230_Inhalt_Inet].dbo.AllUserData on AllUserData.tp_DocId = AllUserDataJunctions.tp_DocId Join [SP230_Inhalt_Inet].dbo.AllLists on AllLists.tp_ID = [AllUserDataJunctions].tp_SourceListId Where tp_Title = 'MySurvey'