How many TV episodes a year is ABC (and/or NBC or CBS) planning to
distribute over the Internet and via Apple iTunes service? How many TV
viewers do the major networks already have, or expect to get, through
Internet services?

http://www.apple.com/itunes/videos/
{For $1.99, you can own the latest episode just one day after it airs.
With full seasons of ?Lost,? ?Desperate Housewives? and ?That?s So
Raven,? plus episodes of new shows like ?Night Stalker? and ?The Suite
Life of Zack & Cody? at your fingertips, you?ll never miss your
favorites.}

you can own the latest episode just one day after it airs:
You can count the amount by checking how many episodes are shown per
week and multiply that with the amount of weeks in year when the show
is being broadcasted. If the show is broadcasted once a week and at
least fifty weeks per year, it would make 50 episodes per show in a
year minimum. If there is 5 shows it makes 250 episodes total per
year.

Currently there are no hard fast numbers. This is an early adoptation
newmedia and it is still in a trial and error stage.
A number of factors still exist. 
   Paid downloads of shows, or on demand streaming. (no copy resides on PC)
   Free downloads of news shows, 20/20, Nightline etc.
How to monitor the success?
   Will there be a NetNeilson/Arbitron to do the actual counting?

As the information age takes it first steps, and the number of home
with broadband increases there will be additional, on demand,
instantaneous information and entertainment streams.

Actually the network's Televison Season is only 24 weeks. Down from
26. Previously the writers strike in the early 2000's lead to less
number of minutes in a show, (For more advertising) and less number of
shows.

Syndicated shows are 5xWeek but there is no hard set rule as to how
many 'repeats' you may get in a month. So the real formula is
incalculatable by laymen. This depends on each individual contract:
Ellen, Maury, Geraldo, Tony Danza, Tyra etc...

So I guess all we can say is 
STAY TUNED