The Trailer Life "2008 Guide to Towing" lists the Sequoia 2WD at 6,500 lbs and the 4WD at 6,200 lbs.
I would suggest becoming knowledgeable on tow ratings including the gross combined tow rating.
The answer is yes it can tow an Airstream depending upon the model you select. Before we purchased our Airstream and tow vehicle I did a lot of research on tow ratings and what tow vehicles were appropriate for which trailer I was considering.
I set up an Excel spreadsheet listing the trailer GVWR, the tow vehicle GVWR and the gross vehicle combined weight rating to insure that I would not exceed the gross vehicle weight rating if I was loaded to the max on both the trailer and tow vehicle. It was interesting and eye opening. I did not want to have to worry about exceeding the weights.
I decided to buy an Airstream 30 classic with a gross vehicle weight rating of 10,000 lbs. I then decided to buy a 3/4 ton pickup (2005 Dodge Ram diesel) with a 9,000 lbs vehicle rating and a combined rating of 20,000 lbs. In my case, I will never exceed the ratings. (10,000 lbs plus 9,000 lbs is less than the combined rating of 20,000 lbs.) The issue with weight is not ability to pull but the ability to stop.
All I'm suggesting is to have a good understanding of the ratings and knowledge of the combination you are considering.
We love our Airstream and tow combination.
2008 Classic 34
Dodge Ram 2500 Quad Cab CTD
AIR #7317 WBCCI #1772 TAC-IL 1