Is not necessary to print your eTA Canada approved. The airline will be able to check from your passport number that your eTA application has been approved.
Once your eTA Canada application has been approved, you will receive your eTA number that starts with the letter “J”. The e-mail will contain a link to open your personal status page, you can verify the status and expiration of your eTA by using the eTA Check Status Tool. To do this, you will need the eTA number noted above and details from the passport you used to apply for your eTA. On that page you can download a PDF document,
Make sure that your passport number are correctly in the PDF document.

I need some contact number, because there are problems with my Visa, and its not possible to pay with my normal Girocard. So what can I do Now?
Dear Birte Razmara,
You must make the payment with a credit card VISA or MASTERCARD.
Regards.