Are teachers less influential nowadays?
I don’t think teachers are less influential nowadays. If teachers only deliver book knowledge to their students, they will soon be replaced by online courses and electronic appliances in the information age. But if teachers still retain their function as those who help the students become more wholistic persons, who help students establish a healthy and optimistic view of the world and who resolve students’ doubts, as teachers in the past few thousand years did, they will still be influential not only to their students, but also to the society, which their students will dominate when they grow up.
With the spread of MOOC--massive online open courses, good teachers are even more influential than any time in the past, or at lease, their influence is a lot faster and  much more widespread. It took Confucius or Socrates hundreds of year to spread his ideas, but it only takes days for Shelly Kagan, a Yale philosophy professor to share with the whole world his perspective of “death” in his open class; or Michael Sandel, Havard professor to refresh our idea about “justice” in his open course, or Tedster like Ken Robison to publicly challenge the education system, Simon Sinek to tell the secret of success, and Jill B Taylor to describe the feeling of death’s approach. They are teachers in a general sense, what they deliver to us is not just knowledge, but the feeling of compassion, understanding and what they try to teach us is not “what”, but “how”, how to see this world and how to understand ourselves.
Mediocre teachers teach, great teachers influence. This doesn’t change with time.