Welcome to the now pretty much dead Forum. The action has moved to Facebook but since I don't do social media, I don't go there.
To answer your question, it looks like your fork can be straightened and may not need to be replaced.
During the 1970's Gitane unlike Peugeot and Motobecane used butted Nervor brand steerers that were decent quality.
A good frame builder or shop with a fork jig should be able to straighten the steerer and realign the forks.
The crown race seat will need to be refaced so that its perpendicular to the steerer.
I'd look into that route first.
You could also try contacting Wayne Bingham, he had some replacement Gitane 531 forks:
Wayne Bingham
Velo Classique
100 East 'O' Street
Purcellville, VA 20132 USA
540-338-8376
Good luck,
Chas.
Chas.
SF Bay Area, CA USA
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1984 Criterium
1969 TdF
1971 TdF
1974 TdF
1984 TdF x 2 Bikes
1970 SC
1971 SC
1972 SC
1984 SC
1984 Team Pro
1985 Professional
1990s Team Replica