The title of Noel Perkins/Gatti Bono's paper can be misleading, lift means not that the fly line is actually lifting but rather the lift force due form/skin drag, which may slow down the downfall for sections of the fly line. (Not that the line is actually lifting, or only for cases where this force would exceed the gravity)On a separate issue, I'm now not convinced that there is an upwards force keeping the loop aerielised. If you look at the 170 backcast video on a log you can clearly see the point of the loop following a parabola. And that's exactly the sort of loop shape that should be lifting. I think that's probably wrong, which annoys me more than anything because we had an argument with Burgess and Tim Rajeff vs Bruce Richards and Noel Perkins very many years ago on the Board before the last Board, which was when and how those PDF documents surfaced. I don't mind Tim being right of course...
We can have a closer look at the question by examining a section of a fly line: Let's say we have an section of a fly line in a air flow with the velocity U with the inclination angle alpha. Due to the form drag an upward component of this force - the lift force FL - is acting on the section of the fly line.
According to  we can determine FN by the following equation (angle alpha > 20°):
FN = 1/2 * CN * rho_f * D * (U * sin(alpha))²
FN: Normal force per unit length (N/m)
CN: Normal force coefficient; ~ 1 for a cylinder
rho_f: Density of the fluid (kg/m³), air ~ 1.225 kg/m³
D: diameter of the cylinder
U: Incoming flow velocity (m/s)
alpha: Inclination angle of the cylinder
I'll leave it to you as an exercise to compute the lift force and compare it to the gravity.
If you can spot a section of a fly line in a video, with an inclination and you know the velocity, you can compute the lift force. It's here also a question of significance and this can be determined.
 2014, Divaret, Forces exerted on a cylinder in near-axial flow
https://www.researchgate.net/profile/Ah ... C%82ow.PDF