You won't have time to linger at Duty Free but this is doable barring a major delay in arriving EWR. Of course would be easier of you had carry on only, but even with checked bag can be OK. At YBQ you should be checked in and bag tagged through to LIS, so you will just drop bag as you exit customs, not have to stand in check in line. Just proceed to security and on to your LIS gate. Have made similarly tight connections at EWR and while it can be nerve wracking, it can be done. And if the worst happens, above advice about having alternate flights to suggest is bang on. .