Nketiah is due to spend a full season at Leeds but has struggled to secure regular minutes, despite his encouraging goal tally.
The 20-year-old missed the Whites' 2-0 win against Queens Park Rangers on Saturday with an abdomen injury and will continue to be assessed 'week-to-week' Bielsa told the club's official Twitter page earlier.
That has fuelled fears that Arsenal will try to recall Nketiah at the next available opportunity, in January, and Bielsa offered little reassurance.
"If he feels comfortable with us this is going to be the key (to whether he will) stay or not," the Argentine said.
Asked whether the England Under-21 star is comfortable at Leeds, Bielsa replied: "It's him that has to say this.
"We are in the same position as to when he arrived at Leeds.
"Our opinion about him is better than the initial (opinion) that we had before he arrived here. That was very good."
Patrick Bamford has continued as Leeds' first-choice centre forward this season, with Tyler Roberts and Ryan Edmondson acting as cover for the £7 million man and Nketiah.
Nketiah is highly-regarded by those associated with Arsenal, including the former Gunners striker Ian Wright, and is said to have spurned a number of rival suitors in favour of a move to Elland Road.
Leeds fans - what effect would Nketiah's return to Arsenal have on your side?
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