How many can seat at this dining table?  

Unsure of what manufacturing...
Unsure of what manufacturing standards there maybe, if any. Where are you Koen?! It seems about right to me. Each person would get roughly 27 inches of side-to-side personal space. That would place 4 persons on either sides and one on either ends of the table.
How will the food be presented? This will make a differnce.

That sounds right
to me. The issue is whether three persons can be seated at a 27 x 41-inch end section -- as I understand it. This is questionable -- I don't think three place mats would fit without overlapping -- but it's doable. You should be able to test this with a table in your home, or at a nearby store. Look for a 41-inch wide table, and measure off 27 inches to test the seating.

That table seats ten, but not the way you're thinking.
Five on each side is the way. 24" x 18" per diner is PLENTY, and this table provides that plus a 5" wide space down the middle of the table for salt & pepper, flowers, candles, etc.

I would think 27 is...
I would think 27 is sufficent, but could go higher...say 35-40 per person in very formal settings. Once you get to 24 and under, it starts to feel crampy. Crampy people aren't as socialable as those with space (elevator effect), and too much space feels impersonable.

I guess it depends on your definition of "comfortable"...
... but five seats on each side gives each person 23.2" x 20.5", which is 475.6 square inches. It would be very unusual to get more than that in any restaurant; most provide 300 to 400 square inches per person, and they don't do it by making the width 27", let alone 35-40".

The issue is really the placement of the legs.
Between the legs on each side, there is 70 inch which is plenty for 2 people but snug for 3. I don't like to have people sitting with the table leg between their legs.
If we do 2 then we will have to squeeze 3 people into a space that is 41x27. Given that the hosts will sit at the end of the table, perhaps we, the hosts, can deal with a tight table space if it ever comes to that.
I tend to like family style meals with people pass the food around. Is 41 going to be enough to have food in the middle?

Certainly it is
unusual to seat people at a residential dining table with no one occupying the ends of the table. Moreover, one never plans a place setting straddling a table leg !
We need to back up and find out how this table grows from 71" to 116" with the addition of two 27-inch leaves. That (literally) doesn't add up.

my mistake
each leaf is 23 inches long. I must have gotten it confused with another table I was looking at. Sorry.

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I suppose it depends on your chairs. And how formal your meals are.
Do you serve 10 often? We seem to have 6 or 20. A party of ten does
require a large amount of food so space in the center would be tight.
A sideboard may be necessary for overflow of dishes. Main course
served by host?
Like SDR mentioned, i see nothing formal sitting picnic table style.
My table is 42 across 85 long. Generous for 6. 8 will work if 2 guests
are small or children.
A pic might help. Here is a total fail i think. Does not fit 6 comfortably
in its compacted position, and forces 3 on the expanded ends so does
not accomodate 8 very successfully.
Ask for more pics from the seller with chair placement or go take a look
if possible. You will know right away if it will work for you.
http://cgi.ebay.com/MID-CENTURY-DANISH-MODERN-ANDERSEN-TEAK-DINING-TABLE...

here is a picture
from the craigslist listing. The leaves seem to be lighter in color but I heard that it is common with older tables. The grain has more knots than what I often see with teak. Is this a good or bad thing?

re: rockland
I love your dining set. It has beautiful color and lines.

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Not my table. I wasn't clear, but the ebay listing is linked under the photo.
I was just trying to visualize what you were describing. Many more photos
are posted in the linked listing and shows what you might be up against
when you try and place three chairs around the end leaves.

Picnic-style seating
I don't like it either, Rockland, but I don't see any other reasonable way to get 10 people around that table. Three people can't fit on one of those 23"x41" leaves, and four can't fit in the 70" space between the legs.
Farmery: If you regularly need to seat 10, maybe you should reject this table and look for one with either four legs at the corners or one leg in the center.

The photo speaks! Agree that...
The photo speaks! Agree that this is not a 10 person table. This to me is a 6 person table extended, 4 person closed.