Many pundits believe that the Dane has the upper hand over Romain Grosjean this year.
Magnussen's fixed contract runs out in 2018, but the American team Haas has an option to extend it for another season.
"We do not comment on the status of contracts," team boss Steiner told BT. "That applies whether it's a driver or a partner.
"Having said that, we are very happy with both of our drivers. We are continuing to focus on this season and scoring as many points as possible."
Haas sit seventh in the constructors' championship after the first three races of 2018.