Eye contact and maintaining that focus is a critical factor of communication between the dog and the trainer / handler. I start fostering and enhancement of eye contact with the pup almost from the moment I receive him or her.
Initially, I tend to use high value treats as edible reinforcement for the pup's display of desired behavior (in this specific case, that being making and maintaining eye contact). Careful timing is employed relative to the pup making and maintaining eye contact, the use of a "behavioral marker" in the form of a "click" as in "clicker training or a word such as "GOOD", and the immediate rewarding of the edible reinforcement. A number of adjustments to the process are made as the pup becomes more proficient at exhibiting the desired behavior, and in relation to elongation of the duration in which eye contact is maintained. These adjustments often involve changing the frequency schedule of reward from continual to intermittent reinforcement, and elongating the period of time the dog must hold visual contact with the trainer before administering reinforcement (the latter often being done in small increments over time). Each pup is different in how fast they develop this highly desirable skill, but most catch on relatively quickly if given frequent opportunity to do so. Taking time to enhance this ability in a pup is easily integrated into pup's overall training program and the dividends paid in increased trainability are well worth the effort.