Yes — you can take Navkarsi the next morning if you ate after sunset.

But remember:

• Eating after sunset is against Jain discipline.
• If you had taken a vow not to eat after sunset, then that vow is considered broken for that day.
• You should do pratikraman / repentance and be more careful next time.

So, in simple words: after-sunset eating does not stop you from taking Navkarsi the next day, but it is still considered a fault in Jain practice.