Yes, there are left luggage facilities in the London Eye Ticket Office where ticket holders can leave their pushchair/buggy free of charge. These must be collected by 7pm.
Alternatively, a pushchair/buggy can come with you onto your Pod at the London Eye but it must remain completely closed/folded throughout the experience, including on the entrance and exit ramps. Please make sure you fold down your buggy prior to joining the boarding queue and only open it once you are out of the attraction.