According to Telefoot (h/t Matt Gault of Football Whispers, via Sky Sports), the Reds "have been closely monitoring [Draxler's] progress" and believe the Germany international could make a strong candidate to replace Coutinho if he leaves.
Draxler has made 11 appearances this season but started just five—none of which were in the UEFA Champions League—and played a total of 472 minutes, an average of just 43 minutes per outing.
Game time is now something of a premium for the German after the arrival of Neymar and Kylian Mbappe in the summer.
Draxler himself only arrived in Paris in January, and he had a positive spell in the second half of last season, per Squawka Football:
The 24-year-old then captained Germany to victory in the FIFA Confederations Cup in the summer, winning the player-of-the-tournament award in the process.
Despite his form, the arrival of more illustrious players has restricted the role he has been able to play, and it seems he'll largely play the role of back-up this year rather than a key member of the side.
As such, it may not be too surprising if PSG were open to selling him in order to save money after the investment put into Neymar and Mbappe.
Draxler is reportedly due a pay rise in January, per ESPN FC's Jonathan Johnson:
It's difficult to justify paying that kind of wage packet to a squad player, even for PSG, whereas at Liverpool he would be among the team's biggest stars, particularly if he replaced Coutinho.
The German is perhaps not quite at the Brazilian's level, but he is an excellent player in his own right. If Coutinho leaves Anfield, Liverpool could do much worse than replacing him with Draxler.