The low loan fee seems odd if they rate him at 50 million Euros, this is a strange strange deal if you ask me and I think the most likely outcome is he becomes a bang average stop gap which is still z very decent deal for the cheap loan fee.
I fancy it's a deal that suits all parties short and long term. Benfica thought they had a gem last year and slapped a 130m buyout clause into his contract, this season he hasn't played as much so Benfica probably feel like they missed their chance to sell him last time around. We need a loan for numbers due to Sissoko getting injured and have pressing issues in the squad to face in the summer so a loan that's as cheap as chips at gives Gedson a new lease of life, that gets him close to his parents again and at worst for Benfica, jogs the memories of teams who may have forgot about him. He joins a physical league, gets to learn from the likes of Mourinho, Ndombele, Sissoko etc and will no doubt return a little more mature if it doesn't work out well for him here.
A big fee on the option side probably gives Benfica a greater opportunity to sell him for something not far off of that figure elsewhere as there are idiot clubs and people who automatically associate a big fee with someone clearly being a better player. A great deal for us in the short term I have absolutely no doubt though.