Here is a code snippet using cURL to post to the Eventbrite REST API and add a custom survey question to your event.
Get Custom Questions:
curl -X GET -H "Authorization: Bearer [API TOKEN HERE]" -H "Cache-Control: no-cache" -H "https://www.eventbriteapi.com/v3/events/[EVENT ID HERE]/questions/?is_owner=1"
Get Specific Question:
curl -X GET -H "Authorization: Bearer [API TOKEN HERE]" -H "Cache-Control: no-cache" -H "https://www.eventbriteapi.com/v3/events/[EVENT ID HERE]/questions/[!!---question_id--!!]/"
Set Custom Question:
curl -X POST -H "Authorization: Bearer [API TOKEN HERE]" -H "Content-Type: application/json" -H "Cache-Control: no-cache" -H -d '{ "question": { "question": { "html": "Another Question - What should it be?" }, "type": "text", "required": true, "choices": [], "ticket_classes": [], "respondent": "attendee" } }' "https://www.eventbriteapi.com/v3/events/[EVENT ID HERE]/questions/"