The average person will chomp down on 7,000 animals during their lives, according to the Vegetarian Calculator
The US life expectancy is 79 year.
The calculator says 15,958 animals for 79 years.
It breaks down to 11 cows, 27 pigs, 2,400 chickens, 80 turkeys, 30 sheep and 4,500 fish, according to the group.
There are rather thorough calculations done at How many animals does a vegetarian save?
This source says 6,982,810,444 chickens were "slaughtered for U.S. supply of meat" in 2013.
The USA population was 316.5 million in 2013.
Assuming people (as opposed to dogs, cats, garbage cans etc.) ate all these chickens, this works out to:
1743 chickens per lifetime.
Similarly the reported 208,511,114 turkeys in 2013 corresponds to:
52 turkeys per lifetime
The reported 97,203,867 pigs in 2013 corresponds to:
24 pigs per lifetime
The reported 34,799,542 cows/calves/cattle corresponds to:
9 "cows" per lifetime
The reported 4,816,359 sheep in 2013 corresponds to:
1.2 sheep per lifetime
USA Today is wrong by a factor of 25 for sheep, and is a little high for the other land animals. Also, USA Today leaves out ducks (24,575,000 in 2013) which correspond to 6 per lifetime.
Additionally, the "How many animals does a vegetarian save?" calculates 148.96 fish including shell fish consumed per person in 2013 in the USA. This is overwhelmingly due to shrimp (126.42), with scallops (4.72) being a distant second.
So 11768 fish per lifetime (mostly shrimp).
In total 13603 animals per lifetime.