Team boss Frederic Vasseur broke the news last week, revealing that reserve driver Kubica and title sponsor Orlen "were satisfied with all of our activities in the most difficult year, which is great news".
Polish oil retailer PKN Orlen's president Daniel Obajtek confirmed: "It pays off for us.
"The advertising equivalent alone amounts to 400 million PLN (about $US 100m)," he said. "This also affects our retail sales.
"Robert is very well received by Poles and abroad, with as many as 70 percent of respondents associating him with our brand," Obajtek added.
It is not yet known if Kubica will combine the ongoing reserve role with a race seat elsewhere.
"Every opportunity to drive an F1 car is something special," the 35-year-old said as he confirmed his ongoing role.
"I am glad that we will be able to continue this cooperation, but it is also very possible that I will be racing in other arenas - something different. Practice makes perfect," Kubica smiled.
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