There is not a fixed 1:1 translation of "I see" to German, as this also depends on the context used.
If it was used in the context given in the example it is fine to use interjections such as "Aha", "Ach so", "Oha", "Gut", "Danke" or the like as an answer but we may also hear a confirming answer like e.g.:
"So viel?" - "So wenig?" - "Das habe ich (nicht) erwartet."
The answers will be different in another context. Below just a few possibilities with an exemplatory German counterpart (way from perfect but intended to show possible variations):
- A: The overall customer satisfaction increases with the price of our product
- B: I see, but isnt quality the major factor still?
Translates: "Ja schon, aber ist die Qualität nicht immer noch der bestimmende Faktor?"
- A: To open the case you will have to pull the slider at the bottom in addition.
- B: I see! Thank you for the hint.
Translates: "Jetzt hab ichs kapiert. Danke für den Hinweis!
- A: You cant upgrade your smart phone because it is too old.
- B: I see. What phones are still supported?
Translates: "Schade! Welche Handys werden denn noch unterstützt?
I believe this list could almost endlessly be extended.