Push affiliate publisher data into google analytics?

I run a blog and publish AWIN affiliate campaigns on my website. The Awin affiliate network offers a transaction feed that automatically push near transaction notifications to a URL I am able to define.

Detailed infos: https://wiki.awin.com/index.php/Transaction_Notification

I wonder if there is a way for me to push/import this data from Awin directly into my Google Analytics account and if so how?

Yes, this feature is called Data Import. What you will need is to choose a dimension (called the import key) with which you can blend GA and AWIN data. Practically, what you might need to do is:

1. Implement a custom dimension as your import key so you can store an affiliate identifier from AWIN against your users in GA, this will be your blending dimension.
2. Create other custom dimensions/metrics as needed to hold the other data points from AWIN
3. Create and import data sets on a regular basis to import new AWIN data

Please note that a few weeks ago Google Data Studio now has a feature to blend data sets, so once step 1 is done, you could perform steps 2 and 3 in data studio (which might be easier for you as you don't need to create the extra dimensions/metrics AND you could have your AWIN data in a Google Sheet synced automatically with your GDS report, thus saving you the data imports).