The playmaker missed Sunday's 2-0 Premier League victory over Everton, where Sokratis made way before half-time with a dead leg.
Sokratis' Greek compatriot and fellow centre-back Konstantinos Mavropanos might have hoped to feature in the third-round fixture but is facing four weeks on the sidelines with a groin injury.
Full-backs Sead Kolasinac and Carl Jenkinson are back in full training after respective knee and ankle injuries.
Long-term absentees Laurent Koscielny (Achilles) and Ainsley Maitland-Niles (broken leg) are aiming to resume training in November.
After starting the Premier League season with back-to-back defeats, head coach Unai Emery has led Arsenal to five consecutive victories in all competitions.
Brentford, meanwhile, suffered a 3-1 defeat at the hands of Frank Lampard's derby at the weekend and lie seventh in the league after nine games.