Old Yeast?

I have an Activator pack in my fridge with a MFG. date of March 23. I bought the pack in mid April but didnt get around to making the beer I planned on making then. Well now I have time but the Mr. Malty yeast pitching starter calculator says I have to have 4 packs of this aged yeast and 3 quarts of wort or buy a new pack and go to a 1.4 quart wort. Is yeast this old really no good? What size starter should I use with this old of a pack on a 1.059 SG beer?

March 23 what year?

Yeast can last  for ridiculously long periods in sterile deionized  water

The viability numbers after 3-4 months really drop off in that calculator.  I believe the numbers but they're the same for every strain and every package, and there must be differences in strains and how each package was handled thru distribution for six-plus months.  I think the numbers came from White Labs, so perhaps they are averages based on lots of testing. 

Try a one-liter starter and see how active it is and how much yeast you have.  If it seems healthy, double up the starter and use it.  If it seems slow or doesn't create a lot of cells, dump it.  Or you could save the time and buy a $2 pack of dry yeast?

Go with Maltlickers advice.
Yeasts generally are viable for much longer than is generally believed
Sane & sound advice with no risk of disappointment.