It's not too difficult to find that out. The population of Earth grows pretty slow - so slow that we can treat it as a constant. (It does not change considerably within a year or two.)
There are 6 billion people on the planet. Let's say the average lifespan is 70 years (all countries combined.) Within 70 years 6 billion people will die, and another 6 billion people will be born to replace them. This means that every year (6,000,000,000/70) = 85.7 million people are born, or 235,000 per day. That's a serious number.
Now, let's assume we have a teleport that accepts a single file of people walking into it. People can walk at 2.5 mph, and you want them to be spaced by 2 yards. 2.5 miles of the line will contain 2,200 people, and they will go through the portal within 1 hour. Since the teleport will not be closing for lunch, 2,200 * 24 = 52,800. So now we know, we need about five teleports - or one large enough to admit five people abreast. This does not look like an impossible requirement, assuming that you have the technology for constructing a teleport across the galaxy :-)
Ah yes, but the emergency requires the evacuation of the entire Earth’s population of 5 billion people and the newborn. At the rate of your teleporter’s 2,200 people per hour, you’ll require more than 311 years to evacuate this 6 billion plus population or 311 of these teleporters or more for one year. This assumes of course the TSA screening and union work stoppages are not included in the estimates....