After reading my take on the comments, I have convinced myself that 观众缘 means audience appeal
人缘(n) = popularity
路人缘 = general appeal /popularity among common folks
观众缘 = audience appeal / popularity among viewers/ audience
有人缘 = popular
有观众缘 = popular among viewers/ audience
Since there's a lively discussion in the comments section arguing about the definition of 人缘, 观众缘, I would give my two cents here.
缘 is something like a 'fated connection', The chance of any two people in different parts of the world would meet is extremely tiny, but somehow people from different part of the world do meet. We called this connection between them 有缘.
when we say someone 有人缘, we are saying this person seemingly fated to connect with many many people, in other words, he is popular among people. People seemingly draw to him by fate.
有观众缘 just replace 人缘 with 观众缘, meaning audience seemingly draw to that person with no apparent reason.
We would not say a super star 有观众缘, because he is so good that people love him for his talent, but we often say a new artist or second string performer 有观众缘-- the audience just like him, as if fate decided so
May be the reason for some audience to like a performer is actually his looks, personality or demeanor. It all seems mysterious to the other audience who can't see anything attractive about the same performer