A lot depends on the stack size as depending on your stack this might not be a good call pre flop or it may be a jam over. Since that is not mentioned I will assume you have something of a decent strong stack of 50 or so big blinds. If that is the case then calling pre flop is perfectly fine to catch a set. In this case we get an anomaly and all cards that flop are below a 7. When villain bets pot (not sure if he always bets pot or varies which makes a big difference here) you need to not only start thinking about what he could have but also start thinking about how willing you are going to be to call future streets. Most turn cards are going to be overcards to our 77 and we will not be very happy. The only turn cards we would really like are a 7 or a 6. Therefore I would be inclined right here at this spot in the hand to make up my mind that I am either going with this hand or Im not. With that being said I dont think you ever call in this spot having position. I would say you should either fold or raise to take control of the hand (raising will also allow you to pot control easier since you have the betting lead). Cant say what I would do exactly but it would be one or the other.
As played with the call on the flop, the turn card is quite good for us. It is one of the few that we don't hate and actually adds to our
equity in the hand. I would say that if I am calling the flop here I would be calling the turn even if it was a jam. Can't really range the opponent at this point but I couldn't on the flop either and we called. I think the
odds of him having a set are weak, I would be more concerned about an overpair myself but the bet does not make a lot of sense to me. If villain has a set why would they bet so large to make us a fold? If they had QQ+, you can say the same as they would make more by having us in the hand rather than getting us to fold out. I really believe based on action the villain has AK or AQ with JJ or 1010 being a possibility. I still think I lean towards calling (again depends on stacks and villain bet sizing tendencies) but if I called the flop I am calling the turn as nothing has changed really except we pickup a draw.