Subs do look a bit high for the number of views they have. Nonetheless, ask yourself if you want to be associated with the channel. Look at their content and decide whether it fits in with yours. The last thing you want to do is jump in the deep end just because you have seen a high sub level from another YouTuber, and attract the wrong audience, and the wrong audience could do more harm then good with dislikes etc.
If you feel their content can relate to yours then go for it, grab the opportunity with both hands as they don't come round often. Although I would first ask some questions, ie. what drew them to your channel in the first place, why they want to interview you, and so on. It gives you some feedback, and at the same time lets you evaluate them as well to make sure things are 'right'.