There are three words that should be looked at for the cross / "stake" consideration. Two are NT Greek, and one is OT Hebrew.
Greek for 4716
stauros {stow-ros'}
Outline of Biblical Usage
1) a cross
a) a well known instrument of most cruel and ignominious punishment, borrowed by the Greeks and Romans from the Phoenicians; to it were affixed among the Romans, down to the time of Constantine the Great, the guiltiest criminals, particularly the basest slaves, robbers, the authors and abetters of insurrections, and occasionally in the provinces, at the arbitrary pleasure of the governors, upright and peaceable men also, and even Roman citizens themselves
b) the crucifixion which Christ underwent
2) an upright "stake", esp. a pointed one, used as such in fences or palisades
This word is found 28 times in the NT and is translated as "cross". We also find this word below which is translated as "tree":
Act 5
30 The God of our fathers raised up Jesus, whom you seized, hanging Him on a tree.
Act 10
39 And we are witnesses of all things which He did, both in the country of the Jews, and in Jerusalem. They did away with Him, hanging Him on a tree.
Greek for 3586
xulon {xoo'-lon}
Outline of Biblical Usage
1) wood
a) that which is made of wood
1) as a beam from which any one is suspended, a gibbet, a cross
2) a log or timber with holes in which the feet, hands, neck of prisoners were inserted and fastened with thongs
3) a fetter, or shackle for the feet
4) a cudgel, stick, staff
2) a tree
Total: 19 - tree 10, staff 5, wood 3, stocks 1; 19
Then we have the OT Hebrew version:
Deuteronomy 21
23 his body shall not remain all night on the tree; but burying you shall bury him the same day. For he that is hanged is a reproach to God. And you shall not defile your land which YHVH your God is giving to you as an inheritance.
Joshua 8
29 And he hanged the king of Ai on the tree until evening time. And at sundown Joshua commanded, and they took his dead body down from the tree, and threw it into the opening of the gate of the city; and raised over it a great heap of stones until this day.
Esther 2
23 And when the matter was searched into, it was found out; and the two of them were hanged on a tree. And it was written in the Book of the Matters of the Days before the king.
Hebrew for 06086
`ets {ates}
Outline of Biblical Usage
1) tree, wood, timber, stock, plank, stalk, stick, gallows
a) tree, trees
b) wood, pieces of wood, gallows, firewood, cedar-wood, woody flax
Total: 328 - tree 162, wood 107, timber 23, stick 14, gallows 8, staff 4,
*****stock 4, carpenter + 02796 2, branches 1, helve 1, planks 1,
*****stalks 1; 328
HT:
It appears that the OT prophecy is pretty clear that it is not a stake, as stake would be a last choice of words for the translation.