Hard to tell, but that tarp in the image does not look all that big. I would guesstimate it to be at the smallest, a 6x8' or at the largest, 6x10'. Either size is too small to be much use in providing an adequate and walled shelter from rain, wind, bugs etc without some serious work.

Cheap tent or not, I still would choose it over the tarp without hesitation. Having a readily sealed shelter from the elements (wind, sun, rain and bugs) makes it a much better option then a tarp any day.

We have a similar "cheap" tent that my neice used when she tagged along with us on camping trips. That cheap tent has easily, 75 sleeping nights in it. So far, the tent has survived rain, snow, wind, flood and to this today, I would not hesitate to use it again for camping - or in a true survival situation. As for the tent fly itself, it measures 45" x 35". Not the largest, but I can think of plenty of uses for the fly in the same survival situation.